"He conjectured, that the soul is seated in a small gland in the brain, called the pineal gland: That there, as in her chamber of presence, she receives intelligence of every thing that affects the senses, by means of a subtile fluid contained in the nerves, called the animal spirits; and that she dispatches these animal spirits, as her messengers, to put in motion the several muscles of the body, as there is occasion."
— Reid, Thomas (1710-1796)
(I.iii, p. 47)
See Thomas Reid, Essays on the Intellectual Powers of Man (Edinburgh and London: Printed for John Bell, and G.G.J. & J. Robinson, 1785). <Link to Google Books>