Of the books in our own language, after deducting those which are obsolete or worthless, there still remain probably 50,000 volumes, which would repay a perusal. Supposing then a person to read 100 pages a day, or 100 volumes a year,-which is more than could well be retained and digested,—it would require 500 years to read all the books worth reading, in the English language alone! This result shows the importance of selection in our reading; or we may misdirect our powers, and misemploy our time, by dwelling on inferior works, and neglecting the nobler and more useful.

Encyclopædias.

From the great multiplicity of books on all subjects of knowledge, arises the utility of Encyclopædias; which, as sources of general information, deserve here a distinct notice. Their name is derived from the Greek παιδεια, learning, from παις, a youth; and έγκυκλιος, circular, from Kukos, a circle; hence it may be defined, the circle of learning Their object is to give a summary of human knowledge; extracted and digested, for the most part, from various works; and accompanied by references to the best authors, on every subject. They are valuable works for occasional use; but most of them are too imperfect to be relied upon; either as giving all the information sought; or the latest information, on subjects which are liable to change or susceptible of improvement.

The earliest summary of human knowledge, appears to have been the books of Hermes, preserved with great care by the Egyptians, and which may be called the Hermiana. Hermes or Mercurius Trismegistus, is the classic name of the Egyptian Thaut, (Thot, Thoth, Thoyt, Theut, or Taaut,) supposed to have been the son of Misraim, and grandson of Ham. He is said to have invented grammar, arithmetic, geometry, astronomy, medicine, and music; and to have engraved his knowledge on pillars of stone. But as the same Egyptian word signifies also a pillar or monument, as well as its guardian deity, the name has doubtless been applied generally to the learning of the Egyptian priests, preserved in monumental inscriptions. Of the forty-two books ascribed to Hermes, some are preserved, including some which are spurious: while others are lost. They treat of the studies above mentioned, together with religion, government, and natural history, as then known.

Similar to these are the twenty-one books of the Persian Zendavesta, or living word, written by Zoroaster, otherwise called Zerdusht. The Persians comprehended all knowledge under the term Magia; and the term magus was synonymous with philosopher or wise man. The Chinese also are said to have an ancient work called Tay Tsing, or San-tsae-too-koey, which treats very fully and systematically of all subjects with which they were acquainted. The only general works left us by the Greeks and Romans, worthy of mention here, are those of Aristotle and Pliny. Aristotle wrote on almost all subjects known to the Greeks, but in various detached treatises while the Natural History of Pliny, though not an exact work of science, is a valuable compendium of ancient learning.

Some works of a general nature were published in the middle

ages: particularly the Speculum of Vincent, which we shall again have occasion to mention: but the term Encyclopædia, appears to have been first introduced by Professor Martinius of Bremen, in his Idea methodicæ et brevis Encyclopædiæ, published in 1606. Another similar work was published by Alstead, in 1620. Three large Encyclopædias have been commenced in Germany; one by Krunitz, which has been extended to 146 volumes; another by Köster, succeeded by J. F. Roos; and a third by Ersch, succeeded by Gruber: but we are not aware that either of these works has been completed. In France, the celebrated Encyclopédie, or Dictionnaire Raisonné, sometimes called the Dictionnaire Encyclopédique, of Diderot, D'Alembert, Voltaire, Condorcet, and other associates, was published in Paris, from 1751 to 1772, in 29 volumes folio; to which 6 volumes were afterwards appended. It promulgated speculative views in philosophy, and liberal opinions in politics; the influence of which had no small share in producing the French Revolution. The Encyclopédie Méthodique, commenced in Paris in 1782, is the largest work ever yet published; having already been extended to 221 quarto volumes, more than 50 of which are of copperplate engravings. It is a collection of dictionaries, each one treating of a distinct branch or department of knowledge; and these dictionaries are arranged simply in alphabetical order.

The first work of this kind, in our own language, if we except the writings of Lord Bacon, which treat of nearly all the subjects of human knowledge, was the Cyclopædia, or universal dictionary of the Arts and Sciences, by Dr. Ephraim Chambers; first published in 1728, in 2 volumes folio; and enlarged in successive editions. Being originally a globe-maker's apprentice, Dr. Chambers wrote some parts of this work, in leisure hours, behind his master's counter. The Encyclopædia Britannica, was first published in Edinburgh, in 1788, in 10 vols. folio, by a Society of Gentlemen in Scotland; James Tytler being the original editor. The seventh edition is now publishing, edited by Prof. Napier. Dr. Rees' Cyclopædia, an enlargement of that by Chambers, was published in London, from 1802 to 1820, and republished in Philadelphia, in 47 volumes quarto, including 6 volumes of plates. It contains much information, especially concerning the Arts; but the subjects are too much subdivided, on account of the alphabetical distribution. Dr. Brewster's Edinburgh Encyclopædia, was commenced in 1810, and republished in New York and Philadelphia, in 18 vols. quarto; the last volume appearing in 1832. It is a highly valuable work; but the latter volumes are less complete than those of the former part of it. The Encyclopædia Metropolitana, the original editor of which was the late Rev. Edward Smedley, was commenced in London, in 1815; to comprise 25 volumes quarto, still publishing. It is arranged, for the most part, according to the connection of the subjects and this alone would in our view give it a preference; aside from its being the latest, on so large a scale.

We have barely room to mention the Encyclopædia Londinensis, by Wilkes, begun in 1796; the Encyclopædia Edinensis, by Millar, begun in 1816; Nicholson's British Encyclopædia, com

menced in 1809; and Partington's British Cyclopædia, printed in 1835-6. The Penny Cyclopædia, conducted by the Society for the Diffusion of Useful Knowledge, was commenced in 1833, and is to be completed in 24 volumes octavo. It is a work of great value. Dr. Lardner's Cabinet Cyclopædia, begun in 1829, in duodecimo, is a valuable series of distinct treatises on the different branches of knowledge; but we have not perceived in it any higher arrangement. An Encyclopædia was printed by Mr. Dobson of Philadelphia, in 21 volumes quarto, 1793-1803. The Encyclopædia Americana, edited by Dr. Lieber, commenced in 1830, and now complete in 13 volumes octavo, is chiefly a translation of the German Conversations Lexicon, alphabetically arranged; and is the most convenient work of reference with which we are acquainted. It has been reprinted in Glasgow.

CHAPTER III.

CLASSIFICATION OF HUMAN KNOWLEDGE.

THE importance of classifying human knowledge, according to some regular system, has been often, if not generally, admitted; and the subject has attracted the attention of many distinguished men, in various ages and countries. As such a classification was the primary object of the present work; the writer is desirous of doing full justice to the labors of his predecessors, in this field of study; before submitting what he believes to be an improved system; with its practical application to the knowledge which is to be classified. A brief review of the different classifications, which have been hitherto attempted, will first be given; for which we are chiefly indebted to a work of much erudition, published in Philadelphia in 1816, by the late judge Woodward, under the title of Encatholepistemia, or a System of Universal Science. This review will be followed by an explanation of the new classification, here proposed; with a summary of the reasons on which it is founded.

Former Classifications of Knowledge.

To the Greeks we must refer, for the earliest classification of human knowledge, of which we possess any information. All their learning was originally comprehended in the term Mathematics; from μανθάνω, I learn ; a term which has since been very much restricted. The introduction of the term Philosopher, by Pythagoras, we have already mentioned. (p. 20.) Pythagoras subdivided the ancient mathematics, with reference to number and magnitude, rest and motion, into the branches of Arithmetic, Music, Geometry, and Astronomy. Music, he regarded as produced by the motion of numbers; and Astronomy, as produced by the motion of magnitudes. These four branches were afterwards called the Quadrivium, from Latin words, signifying the meeting of four roads. To these branches Plato added Physics, or Natural Philosophy; and Theology; under which he probably included both Ethics

and Politics. Aristotle added three other specific branches, Grammar, Rhetoric, and Logic; which have since been called the Trivium, or meeting of three roads; and which, with the Quadrivium of Pythagoras, constituted the seven liberal arts. A course of instruction in these seven arts, was called by the Greeks CYKUKIOS Raideia, or the circle of learning; and hence, as before mentioned, the derivation of the modern word Encyclopædia. The poetical distribution of the sciences among the Muses, will not bear philosophical criticism; but probably belongs to an earlier age.

The Romans borrowed the Seven Liberal Arts of the Greeks; as enumerated in the Latin verse," Lingua, Tropus, Ratio; Numerus, Tonus, Angula, Astra." But Rome, first warlike, and afterwards luxurious, did little to enlarge the boundaries of knowledge; except incidentally, in enlarging the boundaries of her empire and language. Porphyry is said to have been the first who arranged the branches of knowledge in the form of a tree; and the Gnostics, or Platonizing Christians, went so far as to divide all being into material, animal, and spiritual. These are the only Roman classifications of which we can here speak. In the middle or dark ages, little was done for the advancement of science; and still less for its better arrangement. Vincent de Beauvais, (Vincentius Bellovacensis), about the year 1250, summed up the knowledge of those times, in his Speculum Historiale, Naturale, Doctrinale, or historical and philosophical mirror; to which was afterwards anonymously added a Speculum Morale, or view of morals; the preservation of all which, has thrown some light on that obscure period.

The celebrated Francis Bacon, Lord Verulam, usually called Lord Bacon, about the year 1605, made a classification of knowledge, according to the powers of the mind employed in acquiring it; which he considered to be memory, imagination, and reason. To memory he assigned history, which he subdivided into natural and civil; to imagination he ascribed poetry; and to reason he allotted the whole range of philosophy, or the study of the Deity, the human race, and the laws of the material world. He subdivided philosophy into physics and metaphysics; in the latter of which he comprehended mathematics and other heterogenous sciences. Lord Bacon believed in magic and astrology, and denied the earth's diurnal motion; yet, as the author of the Novum Organum, a work in which he pointed out the right method of discovering and applying truth, he is regarded as the great pioneer of modern science.

The French philosopher Descartes, considered all knowledge as either accessory or ultimate; and hence divided it into mathematics, physics, and metaphysics; the latter including theology. The Sieur de Lesclache published a classification of knowledge in a series of engravings and Comenius published another, comprised in one hundred chapters of ten sentences each; the whole containing almost every word in common use. Mr. Hobbes divided all science into knowledge of facts, depending on sensation and memory, and knowledge of consequences, based upon reason. Mr. Locke has also left us a classification of knowledge in three divisions; physica, or the laws of the material world; practica, or rules of human action; and

semiotica, or the means of expressing ideas. Mr. Chambers, the first English Cyclopædist, also prepared a classification of knowledge, in forty-seven distinct branches; arranged as either natural or artificial, internal or external: but in his Cyclopædia, he finally adopted the alphabetical arrangement.

D'Alembert, in his preliminary dissertation on the origin, progress, and affiliation of the sciences, introductory to the great Dictionnaire Encyclopédique, merely revived Lord Bacon's system, with some amendments; but instead of carrying his system into practice, he even doubted whether any satisfactory system could be made; and accordingly the Encyclopædia was arranged in alphabetical order. Baron Bielfield of Prussia, in his Elements of Universal Erudition, also adopted Lord Bacon's system; but with considerable modification in the details. More abstruse classifications have been made by Wronski of Russia in his Programme of Transcendental Philosophy and by the Abbe Mango, of Palermo, in his Acrosofia, or Genealogy of the Sciences.

Returning to England, Sir William Jones made a division of human knowledge into history, arts, and sciences. Dr. Turner of Oxford, divided the same into religion, arts, and sciences. Mr. Horne, in his Introduction to Bibliography, distributes knowledge under the four heads of bibliography, history, philosophy, and literature. In Scotland, Mr. Hume incidentally comprehended all knowledge in the six departments of religion, politics, metaphysics, morals, mathematics, and natural philosophy. Dr. Robertson, the friend of Hume, and like him a historian, comprehended the same in four departments; religion, logic, ethics, and physics. Dr. Beattie, in his Elements of Moral Science, divides knowledge into history, philosophy, mathematics, and poetry; and Dr. Reid has adopted the more natural division, founded on the distinction between body and mind, or material and intellectual objects of thought; but beyond this step, his classification is deemed comparatively imperfect.

In our own country, Dr. Samuel Johnson, the first president of King's, now Columbia College, in New York, prepared a work entitled Noëtica, or a general scheme for the partition of the sciences; in which he divided all knowledge into belles-lettres and philosophy: the former including grammar, rhetoric, eloquence, history, poetry, and criticism; and the latter comprehending mathematics, mechanics, physics, and astronomy, together with metaphysics and ethics, embracing psychology, theology, economics, and politics. In this arrangement, the distinction between sciences and arts was entirely neglected; the theoretical and practical parts of knowledge being presented, throughout, in combination. This work was published by Dr. Franklin in Philadelphia; and reprinted in London,—but without the title.

The late President Jefferson devoted much attention to this subject; both in classifying the books of his own Library; and in arranging the professorships of the University of Virginia. Mr. Jefferson adopted Lord Bacon's principle of classifying knowledge, according to the mental powers employed; and he assigned to memory, civil and natural history; to reason, moral and natural