MADAM,
Concerning Sense and Perception, your Authors opinion is,[1] That it is made by a motion or impression from the object upon the sensitive organ, which impression, by means of the nerves, is brought to the brain, and so to the mind or soul, which onely perceives in the brain: Explaining it by the example[2] of a Man being blind, or walking in dark, who by the help of his stick can perceive when he touches a Stone, a Tree, Water, Sand, and the like; which example he brings to make a comparison with the perception of Light; For, says he, Light in a shining body, is nothing else but a quick and lively motion or action, which through the air and other transparent bodies tends towards the eye, in the same manner as the motion or resistance of the bodies, the blind man meets withal, tends thorow the stick towards the hand; wherefore it is no wonder that the Sun can display its rays so far in an instant, seeing that the same action, whereby one end of the stick is moved, goes instantly also to the other end, and would do the same if the stick were as long as Heaven is distant from Earth. To which I answer first, That it is not onely the Mind that perceives in the kernel of the Brain, but that there is a double perception, rational and sensitive, and that the mind perceives by the rational, but the body and the sensitive organs by the sensitive perception; and as there is a double perception, so there is also a double knowledg, rational and sensitive, one belonging to the mind, the other to the body; for I believe that the Eye, Ear, Nose, Tongue, and all the Body, have knowledg as well as the Mind, onely the rational matter, being subtil and pure, is not incumbred with the grosser part of matter, to work upon, or with it, but leaves that to the sensitive, and works or moves onely in its own substance, which makes a difference between thoughts, and exterior senses. Next I say, That it is not the Motion or Reaction of the bodies, the blind man meets withal, which makes the sensitive perception of these objects, but the sensitive corporeal motions in the hand do pattern out the figure of the Stick, Stone, Tree, Sand, and the like. And as for comparing the perception of the hand, when by the help of the stick it perceives the objects, with the perception of light, I confess that the sensitive perceptions do all resemble each other, because all sensitive parts of matter are of one degree, as being sensible parts, onely there is a difference according to the figures of the objects presented to the senses; and there is no better proof for perception being made by the sensitive motions in the body, or sensitive organs, but that all these sensitive perceptions are alike, and resemble one another; for if they were not made in the body of the sentient, but by the impression of exterior objects, there would be so much difference betwixt them, by reason of the diversity of objects, as they would have no resemblance at all. But for a further proof of my own opinion, did the perception proceed meerly from the motion, impression and resistance of the objects, the hand could not perceive those objects, unless they touched the hand it self, as the stick doth; for it is not probable, that the motions of the stone, water, sand, &c. should leave their bodies and enter into the stick, and so into the hand; for motion must be either something or nothing; if something, the stick and the hand would grow bigger, and the objects touched less, or else the touching and the touched must exchange their motions, which cannot be done so suddenly, especially between solid bodies; But if motion has no body, it is nothing, and how nothing can pass or enter or move some body, I cannot conceive. 'Tis true there is no part that can subsist singly by it self, without dependance upon each other, and so parts do always joyn and touch each other, which I am not against; but onely I say perception is not made by the exterior motions of exterior parts of objects, but by the interior motions of the parts of the body sentient. But I have discoursed hereof before, and so I take my leave, resting,
Madam,
Your faithful Friend
and Servant.
[1] Philos. part. 4. a. 189.
[2] Diopt. c. 1. a. 2, 3. & c. 4. a. 1.
[XXXVIII.]
MADAM,