of mutually dependent quantities, by supposing them to vary, and observing their relative changes, was the last and highest step in Mathematics.

In analyzing the material world, we first observe the great distinction between animate and inanimate bodies: the latter having no innate principle of life, nor power to move or act, or cease from action, except when influenced by some external cause, or force. The study of these forces and their laws of action is the object of Natural Philosophy; which shows us, that light, heat, and electricity,-even clouds and storms, lightning and thunder,—are all subject to the same general laws; and that the stars of heaven, rolling on through countless ages, with the earth itself, the star which we inhabit, obey, in all their motions, the simple law of gravitation, which causes the uplifted stone to fall to the ground. Before leaving inanimate matter, it remains to consider its composition: and we find in it an immense variety of compounds, all resulting from a few simple elements. This leads to the study of the means by which those elements may be compounded or disunited, with the nature and uses both of the elements and of their compounds; in all of which consists the science of Chemistry.

In studying animated nature, we find a principle of life, modifying the laws of inanimate matter. Hence we have a new class of phenomena, in the origin, growth, and decay of organic bodies, whether plants or animals; and hence a higher interest attaches to the studies of Botany and Zoology. In the animal races, we find an additional principle of life, inciting them to action, and though far inferior, yet in many respects similar to the human intellect. This principle becomes more prominent, as we rise to the higher orders of animals; and as they approach the human race in outward form and physical constitution. The fact that many of these organic forms are found buried in the depths of the earth, here arrests our attention; and leads us to investigate the structure of our globe; first in its homogeneous elements, and afterwards in their massive aggregations. Hence arose the sciences of Mineralogy and Geology; which, in connection with those relating to organic life, complete the range of Natural History.

Man, being essentially compounded of mind and matter, seems to form the great connecting link between the material and the spiritual world. Considering his material nature, we are first led to study the structure of the human body; especially as affording the means of detecting the diseases to which it is liable, and suggesting their appropriate remedies. If the study of Medicine originally preceded that of Anatomy and Physiology, it could have made but little progress until these studies were considerably advanced, and some theoretical views adopted concerning the action of remedial agents, by which they might be classified and compared. The Art of Healing was thus improved empirically, until it became a science; resting on acknowledged principles, though of difficult application and the introduction of mechanical agency, or the practice of Surgery, rendered its functions complete.

The human body, owing to its physical constitution, requires shelter, food, and clothing: to supply which, has exercised the ingenuity,

and incited the labors of the greater portion of our race. Hence have arisen the Arts of Construction and Conveyance; by which not only man himself, but the objects to which he attaches the greatest value, may be protected from the elements; or transported from place to place, though mountains rear their crests, or oceans roll between. Hence Agriculture, Manufactures, and Commerce, have sprung from the bosom of the earth; and with linked hands, and united labors, they have increased and developed the productions of nature, or moulded and modified them, to suit the wants of humanity :-then sent them forth into all lands, in exchange for other commodities; until the world has become as it were a family of nations, each engaged in contributing to the general welfare.

Unhappily for the cause of human improvement, this concord is liable to interruptions; when nations, like individuals, yield to their angry passions, and, deaf to the voice of reason and justice, rush to the battle field;-far oftener, to gratify their unhallowed ambition, or to avenge fancied wrongs, than to defend the sacred cause of freedom. Thus, the Arts of War have become a part of human knowledge, necessary in self-defence; though for this sacred object alone can we deem their practice justifiable, or allowable. By their potent aid, a feeble nation, though powerless to carry its attacks abroad, and commit aggressions upon others, may yet be strong to resist aggressions, amid its mountain fastnesses, or behind its fortified walls. Thus provided and protected, the human mind gives scope to other wants, more refined and intellectual; and in the assemblage of beautiful forms, rich colors, harmonious sounds, and graceful exercises, it seeks for occupation and amusement. To leisure, inspired by genius, and guided by taste, do the Fine Arts, the last which relate to material objects, owe their interest, and their being.

Considered intellectually, man was evidently destined for a state of society and hence the gift of speech was bestowed, which so far exalts him above the brute creation. The cultivation of this faculty, led to the study of Grammar, and of the various Languages which have arisen among men; emanations, doubtless, from one primitive tongue. By their aid, history has recorded its facts; philosophy, its speculations; science, its principles; and art, its processes: in short, by their aid, most of the knowledge has been preserved and diffused, which forms the boast and distinction of our race. From the means of communicating our thoughts, we naturally ascend to the source from which they spring: and thus we arrive at the study of the human mind, with its varied faculties and relations; which collectively form the subject of the Mental Sciences; including Rhetoric, Logic, Mental and Moral Philosophy, and Education.

Regarded as social beings, we owe certain duties to our fellowmen, and claim certain rights from them in return. The enforcement of these duties, and the preservation of these rights, is found to require the exercise of power, lodged in some proper hands. Hence govern

ments have originated, and laws been framed; the study of which has expanded into the extensive, and important science of Jurisprudence; associated with Politics and Political Economy. Again, viewing man in relation to his Creator, new duties arise, which indeed include all

the others; and of which a right understanding is essential, both to our present and future happiness. Hence the origin of Theology; in whose sublime inquiries, the light of nature is aided by the light of Revelation, shining on the straight and narrow path to life eternal. Beyond this light, and up to the higher orders of being, darkness still surrounds us; and probably it will continue, until this mortal shall put on immortality, and this dawn give place to perfect day.

The principles involved in these intellectual sciences, find their application, as well as their illustration, in the study of mankind at large, nations and individuals. This study naturally commences with Geography, or a description of the earth and its inhabitants : tracing their locations; manners and customs; resources and improvements; as derived from statistical records, and the accounts of Voyagers and Travellers. From Geography we naturally proceed to History: whose voluminous records display the varied fate of nations, during the lapse of time; unfolding the causes of their rise and advancement, or of their decline and destruction: thus proving that pure religion and virtue are the only safeguards of a state; while wealth, producing luxury, is a temptation to invasions from abroad and dissensions within.

The study of nations is greatly elucidated, by tracing the career of those remarkable individuals, who have guided the current of public events, or opened new fountains of knowledge; and thereby stamped their character upon their own times, or exerted an influence upon succeeding ages. Thus, Biography supplies those details which are beyond the limits of History; and each aids the other in exhibiting a full picture of human nature, both in its darker and its brighter aspects. This picture may also be seen by reflected light, in the pages of Poetry and Romance: which represent human character and actions according to the ideas of the poet and the novelist: often imbodying the shadowy forms of fancy, as well as the sober realities of truth; while showing, as in a mirror, the views which they have entertained of life, in all its vicissitudes. Their writings possess various degrees of merit; but a selection from the best of them can by no means be omitted, in completing the cycle of human knowledge.

Thus, passing from the material to the intellectual world, we have glanced hastily over the most prominent of those subjects, for the arrangement and examination of which, the present work was undertaken. If this survey has been too brief, to give an adequate idea of the object in view, it should be remembered that the greatest objects appear small, when seen in distant perspective. Could a volume be substituted for every page of the present work, it would still be insufficient to contain the sum total of human knowledge; the most important points of which may yet be comprehended in a single tome; as the widest landscape may be seen through a single pane of glass.

CHAPTER II.

SOURCES OF HUMAN KNOWLEDGE.

Of all the information which we possess, a large, if not the larger portion, is derived, either directly or indirectly, from our fellow-men. Hence arises the distinction between original and communicated knowledge; founded on the manner in which it is obtained. The term original knowledge, strictly applies to that which was first discovered by its possessor; being previously unknown to any person whatever: while such knowledge as has been derived from others, but afterwards verified by ourselves, may properly be called personal knowledge, though it be not original. The knowledge of events, which we acquire from others, and which, owing to their transient nature, can be verified or proved only by testimony, may be distinguished as historical; in contradistinction from which, the knowledge of general facts may be called experimental; and the knowledge of general principles, obtained by reasoning or calculation, may be termed scientific.

We may acquire a personal knowledge of scientific facts, and principles, at any time, by voluntary application: but a personal knowledge of transient events, must, from its nature, be confined to those who witnessed them; though others may know them historically. Another distinction of knowledge, especially in regard to the arts, is that of speculative and practical. Speculative knowledge may be communicated, or derived, by study; but practical knowledge can only be acquired by an actual performance of the process in question; whatever it may be. Personal knowledge, then, may be acquired by observation or experiment; by reasoning or by calculation and that knowledge which has been verified by others, as well as by ourselves, is perhaps the most certain of all.

Communicated knowledge may be derived from monuments, statues, coins, or other antiquities; from books or manuscripts, pictures or engravings; and from conversation, gestures, or signals, in immediate intercourse with our fellow-men. Of all these sources of knowledge, books and conversation are, at the present day, much the most important. Conversation may produce the liveliest impressions upon the mind; but those impressions, once effaced, cannot always be restored: while books have the countervailing advantage, that we can recur to them at pleasure, and revive the ideas which they have furnished, although long lost or forgotten. In developing this subject farther, we shall treat, 1. Of the Ancient Schools of Philosophy; 2. Of Modern Learned Societies; 3. Of Libraries; and, 4. Of Encyclopædias.

The Ancient Schools of Philosophy.

Philosophy was formerly understood to comprehend the principles of all human knowledge; or, in the words of Cicero, "the knowledge of things divine and human, and of the causes by which they are

governed." It extended therefore to God and spiritual beings; man and all animals; the earth and the starry heavens; matter and mind, and all their properties or attributes. The name philosopher, is derived from the Greek, pos, a friend or lover; and copos, a sage, magus, or wise man. It was introduced by Pythagoras ;-who modestly declined the title of sophist, or wise man, but styled himself a lover of the wise, or of wisdom. Philosophy has also been defined, "the science of the fundamental truths of human knowledge;" or "the science of reason;" and it has been subdivided into Natural, Mental, Moral, and Metaphysical Philosophy; of which divisions we shall speak hereafter.

In ancient Greece, where knowledge was so much cultivated, it was disseminated, to a great extent, by the oral instructions of the philosophers; and perpetuated by means of the schools, or sects, which they founded. Those schools, considered as sources of knowledge, we may here properly mention. The first of them was the + Ionic school, or sect, founded by Thales, of Miletus, in Ionia, who died about 548 B. C. He taught that water, or rather fluidity, was the great principle of life and activity, throughout nature; and hence he called it the divine principle, or the soul of the world. Having travelled in Egypt, he acquired and even extended the science of geometry; and he is said to have been the first who predicted an eclipse. He taught that the stars were material: but believed in the existence of demons, or spirits, pervading the universe; and ascribed souls to inanimate objects.

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The second important school, or sect, was the Italic, founded by Pythagoras, of Samos, who died about 506 B. C. He travelled in Chaldea and Egypt, and finally retired from Greece, to Magna Græcia, in Italy, where he established his school. He taught that the sun is a great central fire, the principle of warmth and life; that the planets revolving around it must be ten in number, because he regarded ten as a perfect number; and that by dividing the ether in their course, they produced tones, varying with their size, distance, and velocity, which together composed the harmony of the spheres. He believed that the Deity, or Universal Spirit, is in substance similar to light; a monad or unit, from whom gods, demons, heroes, and human souls emanated; and that the human soul consists of two parts, the one residing in the heart, sentient and perishable; the other residing in the brain, rational and immortal; which, on leaving the body, assumes an ethereal vehicle, till it enters some other human or animal body, to be farther purified, before admission to the divine presence.

Contemporary with Pythagoras was Xenophanes, who settled about 536 B. C. at Elea, and founded the Eleatic school. He maintained that God is the only being; in whom all others are comprehended; and that the variety of forms and objects in nature is not real, but only imaginary. He believed that all things are produced from fire, air, and water; and contended that the moon was inhabited. The Socratic school was founded by Socrates, of Athens, who died a martyr to virtue and truth, 400 B. C. Rejecting the wild hypotheses and fallacies of the Sophists, or speculative philosophers,