One thing, however, is quite clear, that the simple abstractions above spoken of, and the more complex abstractions every day in our mouths, as justice, virtue, truth, &c. are all derivatives from objects of sense; and that even fancy or imagination, however wild or capricious, when "bodying forth the forms of things unknown, and turning them to shape," does nothing more than compound the simple ideas derived from sensation, A sphynx, a centaur, a phoenix, or a unicorn, is made up of members with which we are all of us familiar. And, to add authority to illustration, D'Alembert observes, "Imaginari, nihil aliud est quam rei corporea figuram seu imaginem contemplari ;" whilst Stewart remarks, "That the abstractions of the Poet amount to nothing more than to a separation into parts of the realities presented to his senses."

From what has just been said, we are bound to infer, that the senses are the only inlets of knowledge. There being no knowledge which cannot be referred to sense.

I speak not here of Revelation, which can furnish no objection to the reasoning of this Essay. That Being who contrived five inlets of knowledge for

of thinking might be added to matter."-"Cave ne unquam simile veri putaveris, quod Aristoxenus dixit; mentem omnino nullam esse; sed quasi harmoniam in fidibus ex constructionė corporis, et compagibus viscerum, vim sentiendi existere.”

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our œconomy in this world, can, assuredly, add a sixth whenever it suits his all-gracious designs to do so. But whether it was by any means analogous to sensation, that "holy men of old," prophets and apostles, received communications from heaven, in "dreams and visions," as we cannot understand, neither shall I endeavour to explain. One thing most important for us to know, has been afforded us; viz. that such communications were, what they professed to be, "the word of the Lord." This was abundantly proved by the evidence of miracles; an evidence, whilst it is the only one upon which the truth of revelation can stand, is the most conclusive and satisfactory that the mind can ask. And I may further add, that if the mode of deriving the truths was peculiar, the truths themselves were, every one of them, made up of sensible objects.

But if there be any one who thinks that he has an idea existing in his mind which had not its origin in sensation; or which has not a necessary connexion with sensible objects, I shall be glad to be told what that idea is, and by what method it was acquired. So necessarily are all our notions confined to objects of sense, that the whole of Paradise Lost (though a great portion of that sublime poem, concerns Spiritual Beings) consists of them; whilst in Scripture, we find the same attributes ascribed to God himself, which properly belong to man: had it been otherwise, they would have been,

like the vision of St. Paul, already alluded to, "impossible for man to conceive" them.

Let this fundamental truth be remembered; it is the key with which I hope to unlock the mind, and to shew that there is no such a tenant dwelling in it as Genius.

My first conclusion, drawn from the above truth, is obvious and incontestible-viz, that since all knowledge is derived, originally, through the medium of the senses, therefore, all knowledge must gradate with the perfection of the senses. This I will endeavour to illustrate by a few examples. And as we acquire a large portion of our acquaintance with external nature by the eye, I shall chiefly confine my observations to that organ: whilst it cannot be denied, that what is clearly proved of one sense, will be equally conclusive of all.

The naval officer, mentioned by Dr. Nichols, "who purchased a blue uniform coat and waistcoat with red breeches to match the blue," would certainly have never discovered the composition of light; nor ever have formed a Genius in Botany or Painting. As a Botanist he would have described a violet and a rose as of the same color; and had he exercised his pencil as an Artist, to represent an eruption of Ætna or Vesuvius, he would, probably, have colored the sky red, and have painted the fire blue and had his object been the human figure, a naval officer for example, he would have "matched a blue uniform coat and waistcoat with

red breeches," to the no little surprise and discomfiture of the unlucky object who had sate for his likeness; and who, perhaps, had indulged complacent hopes of looking on the canvas unutterable things; but multum abludit imago!

Even to the celebrated Mr. Dalton, the red rays of the solar spectrum were scarcely visible; the whole appearing to consist of yellow and blue; and Mr. Huddart mentions the case of one Harris, that could only distinguish "black and white;" and he had two brothers almost equally defective; one of whom always mistook "orange for green." Perhaps the eyes of the whole family were required to see the entire spectrum.

To all these individuals, "knowledge" of a peculiar kind "from one entrance," as Milton pathetically exclaims, was "quite shut out." How could the different refrangibility of the different rays of light have ever been discovered, had all mankind possessed such organs of vision as these? Insuperable perplexities would have confounded their observation. To the naval officer, the red and blue rays, having nothing to distinguish them from each other, would have presented an inexplicable appearance ;-viz. that of similar rays with different degrees of refrangibility; whilst to Mr. Dalton, the red rays would have been lost, and the orange or yellow have occupied a double portion in the spectrum. To Harris the prism would have afforded no information whatever. I need not draw

your attention to the achromatic telescope, or to the arts of the Dyer, with which mankind would have had but little acquaintance under circumstances of vision like these. So far therefore, knowledge of this kind, depends upon sense; nor could any power of Genius supply the defect out of its own imaginary resources.

But it is not Philosophy and the arts of life alone that would be narrowed by this imperfection of vision; not Botany and Painting only among the "ingenuas artes," that would be repressed; but the intellectual loom of the Poet would also be deprived of much of its most beautiful materiél ; now furnished by the varied scenery of nature. Had Mr. Dalton been a votary of the muses, instead of a disciple of Philosophy, we should never have heard, in his pastoral songs, of "flowery vales, and verdant fields;" but on every side have beheld nothing but "yellow meads of asphodel." Birds, beasts, and trees, rivers, and plains, would have stood before us in burnished gold. Whilst a profile darkness, or a colorless brilliancy, would have alternated in the lifeless description of Harris. Nor would Shakespeare have ever entertained the sublime thought, of making "the green, one red.' I need not multiply examples; numberless will press themselves upon the recollection of all who hear me, in illustration of this truth; and every one of them will serve to confirm the doctrine of this Essay that sense alone supplies knowledge, and