Date: c. 501 B.C.

"One would never discover the limits of soul, should one traverse every road--so deep a measure does it possess."

— Heraklitus (fl. 504-1 BCE)

Date: 1711

"And reflecting on what is transacted within us, it seems to me a very diverting Scene to think when we strive to recollect something that does not then occur; how nimbly those volatil Messengers of ours will beat through all the Paths, and hunt every Enclosure of the Organ set aside for thinking...

— Mandeville, Bernard (bap. 1670, d. 1733)

Date: 1741

"Their Understandings are hereby cooped up in narrow Bounds, so that they never look abroad into other Provinces of the intellectual World, which are more beautiful perhaps and more fruitful than their own."

— Watts, Isaac (1674-1748)

Date: 1748, 1777

"Chaced from the open country, these robbers [i.e., superstitions] fly into the forest, and lie in wait to break in upon every unguarded avenue of the mind, and overwhelm it with religious fears and prejudices."

— Hume, David (1711-1776)

Date: September 1, 1759.

"The incursions of troublesome thoughts are often violent and importunate; and it is not easy to a mind accustomed to their inroads to expel them immediately by putting better images into motion; but this enemy of quiet is above all others weakened by every defeat; the reflection which has been o...

— Johnson, Samuel (1709-1784)

Date: January 1762

"C’est lui qui porte le flambeau au fond de la caverne; c’est lui qui apprend à discerner les motifs subtils et déshonnêtes qui se cachent et se dérobent sous d’autres motifs qui sont honnêtes et qui se hâtent de se montrer les premiers. Il souffle sur le fantôme sublime qui se présente à l’entré...

— Diderot, Denis (1713-1784)

Date: 1763 (repr. 1776); 1794 (repr. 1799)

"When a train of ideas is very familiar to the mind, they often follow one another in the memory without any laborious recollection, and so as to arise almost instantaneously and mechanically; as in writing, singing, &c. the traces between them being worn like beaten roads."

— Doddridge, Philip (1702-1751)

Date: 1776

"Hence the strange parade he makes with regions, and recesses, hollow caverns, and private seats, wastes, and wildernesses, fruitful and cultivated tracks, words which, though they have a precise meaning as applied to country, have no definite signification as applied to mind."

— Campbell, George (1719-1796)

Date: 1782

"Were I poetically turned--what a glorious field for fancy flights--such as the blue-eyed Goddess with her flying carr--her doves and sparrows, &c. &c.--Alas! my imagination is as barren as the desert sands of Arabia."

— Sancho, Charles Ignatius (1729-1780)

Date: 1790, 1794, 1795, 1818, 1827

"For man has closed himself up, till he sees all things thro' narrow chinks of his cavern."

— Blake, William (1757-1827)