"As all our knowledge of the material world is derived from the information of our senses, natural philosophers have, in modern times, wisely abandoned to metaphysicians, all speculations concerning the nature of that substance of which it is composed; concerning the possibility or impossibility of its being created; concerning the efficient causes of the changes which take place in it; and even concerning the reality of its existence, independent of that of percipient beings: and have confined themselves to the humbler province of observing the phenomena it exhibits, and of ascertaining their general laws."

“What we commonly call sensibility, depends, in a great measure, on the power of imagination. Point out two men, any object of compassion; --a man, for example, reduced by misfortune from easy circumstances to indigence. The one feels merely in proportion to what he perceives by his senses. The other follows, in imagination, the unfortunate man to his dwelling, and partakes with him and his family in their domestic distresses.... As he proceeds in the painting, his sensibility increases, and he weeps, not for what he sees, but for what he imagines. It will be said, that it was his sensibility which originally aroused his imagination; and the observation is undoubtedly true; but it is equally evident, on the other hand, that the warmth of his imagination increases and prolongs his sensibility.”

“THE prejudice which is commonly entertained against metaphysical speculations seems to arise chiefly from two causes: First, from an apprehension that the subjects about which they are employed, are placed beyond the reach of the human faculties; and, secondly, from a belief that these subjects have no relation to the business of life.”

“With the respectability of the senses and feelings established, textbooks written by the Scottish philosophers began to include such topics as perception, memory, imagination, association, attention, language, and thinking. Such a textbook was written by Dugald Stewart , titled Elements of the Philosophy of the Human Mind , and was used at Yale University in 1824.”

“Among the various subjects of the inquiry, however, which, inconsequence of the vague use of language, are comprehended under the general title of metaphysics, there are some, which are essentially distinguished from the rest, both by the degree of evidence which accompanies their principles, and by the relation which they bear to the useful sciences and arts: and it has unfortunately happened, that these have shared in that general discredit, into which the other branches of metaphysics have fallen. To this circumstance is probably to be ascribed, the little progress which has hitherto been made in the PHILOSOPHY OF THE HUMAN MIND; a science, so interesting in its nature, and so important in its applications, that it could scarcely have failed, in these inquisitive and enlightened times, to have excited a very general attention, if it had not accidentally been classed, in the public opinion with the vain and unprofitable disquisitions of the schoolmen.”

“Nothing, in truth, has such a tendency to weaken not only the powers of invention, but the intellectual powers in general, as a habit of extensive and various reading without reflection.”

“Every man has some peculiar train of thought which he falls back upon when he is alone. This, to a great degree, moulds the man.”