Philosophical Letters: or, modest Reflections upon some Opinions in Natural Philosophy. Duchess of Margaret Cavendish Newcastle

When the Motion of the ambient æthereal substance makes the spirits and fluid parts of our bodies tend outwards, we acknowledg heat, but by the indeavour inwards of the same spirits and humors we feel cold: so that to cool is to make the exterior parts of the body endeavour inwards, by a motion contrary to that of calefaction, by which the internal parts are called outwards. He therefore that would know the cause of Cold, must find by what motion the exterior parts of any body endeavour to retire inwards. But I desire you to consider, Madam, that there be moist Colds, and dry Heats, as well as dry Colds, and moist Heats; wherefore all sorts of Cold are not made by the retyring of parts inwards, which is contraction or attraction; neither are all sorts of Heat made by parts tending outwards, which is dilation or rarefaction; for a moist cold is made by dilation, and a dry heat by contraction, as well as a moist heat is made by dilation, and a dry cold by contraction: But your Author makes not this difference, but onely a difference between a dilated heat, and a contracted cold; but because a cold wind is made by breath blown thorow pinched or contracted lips, and an hot wind by breath through opened and extended lips, should we judg that all heat and cold must be made after one manner or way? The contracted mouth makes Wind as well as the dilated, but yet Wind is not made that way, as heat and cold; for it may be, that onely the air pressed together makes wind, or it may be that the corporeal motions in the air may change air into wind, as they change water into vapour, and vapour into air; or it may be something else that is invisible and rare, as air; and there may be several sorts of wind, air, heat, cold, as of all other Creatures, more then man is capable to know. As for your Authors opinion concerning the congealing of Water, and how Ice is made, I will not contradict it, onely I think nature hath an easier way to effect it, then he describes; Wherefore my opinion is, that it is done by altering motions; as for example, the corporeal motions making the figure of water by dilation in a Circle figure, onely alter from such a dilating circular figure into a contracted square, which is Ice, or into such a contracted triangle, as is snow: And thus water and vapour may be changed with ease, without any forcing, pressing, raking, or the like. The same may be said of hard and bent bodies; and of restitution, as also of air, thunder and lightning, which are all done by an easie change of motion, and changing into such or such a figure is not the motion of Generation, which is to build a new house with old materials, but onely a Transformation; I say a new house with old materials; not that I mean there is any new Creation in nature, of any thing that was not before in nature; for nature is not God, to make new beings out of nothing, but any thing may be called new, when it is altered from one figure into another. I add no more at this time, but rest,

      Madam,

      Your faithful Friend

      and Servant.

[1] C. 28. a. 1.

XXII.

       Table of Contents

      MADAM,

The Generation of sound, according to your worthy Authors opinion, is as follows: As Vision, says he,[1] so hearing is Generated by the medium, but not in the same manner; for sight is from pressure, that is, from an endeavour, in which there is no perceptible progression of any of the parts of the medium, but one part urging or thrusting on another, propagateth that action successively to any distance whatsoever; whereas the motion of the medium, by which sound is made, is a stroke; for when we hear, the drum of the Ear, which is the first organ of hearing, is strucken, and the drum being stricken, the Pia Mater is also shaken, and with it the arteries inserted into it, by which the action propagated to the heart it self, by the reaction of the heart a Phantasme is made which we call Sound. Thus far your Author: To which give me leave to reply, that I fear, if the Ear was bound to hear any loud Musick, or another sound a good while, it would soundly be beaten, and grow sore and bruised with so many strokes; but since a pleasant sound would be rendred very unpleasant in this manner, my opinion is, that like as in the Eye, so in the Ear the corporeal sensitive motions do pattern out as many several figures, as sounds are presented to them; but if these motions be irregular, then the figure of the sound in the ear is not perfect according to the original; for if it be, that the motions are tyred with figuring, or the object of sound be too far distant from the sensitive organ, then they move slowly and weakly, not that they are tyred or weak in strength, but with working and repeating one and the same object, and so through love to variety, change from working regularly to move irregularly, so as not to pattern outward objects as they ought, and then there are no such patterns made at all, which we call to be deaf; and sometimes the sensitive motions do not so readily perceive a soft sound near, as a stronger farther off. But to prove it is not the outward object of sound with its striking or pressing motion, nor the medium, that causes this perception of sense, if there be a great solid body, as a wall, or any other partition betwixt two rooms, parting the object and the sensitive organ, so, as the sound is not able to press it, nevertheless the perception will be made; And as for pipes to convey sounds, the perception is more fixt and perfecter in united then in dilated or extended bodies, and then the sensitive motions can make perfecter patterns; for the stronger the objects are, the more perfect are the figures and patterns of the objects, and the more perfect is the perception. But when the sound is quite out of the ear, then the sensitive motions have altered the patterning of such figures to some other action; and when the sound fadeth by degrees, then the figure or pattern alters by degrees; but for the most part the sensitive corporeal motions alter according as the objects are presented, or the perception patterns out. Neither do they usually make figures of outward objects, if not perceived by the senses, unless through Irregularities as in Mad men, which see such and such things, when as these things are not neer, and then the sensitive motions work by rote, or after their own voluntary invention. As for Reflexion, it is a double perception, and so a double figure of one object; like as many pictures of one man, where some are more perfect then others, for a copy of a copy is not so perfect as a copy of an original. But the recoyling of sound is, that the sensitive motions in the ear begin a new pattern, before they dissolved the former, so as there is no perfect alteration or change, from making to dissolving, but pattern is made upon pattern, which causes a confusion of figures, the one being neither perfectly finished, nor the other perfectly made. But it is to be observed, that not always the sensitive motions in the organs take their pattern from the original, but from copies; as for example, the sensitive motions in the eye, pattern out the figure of an eye in a glass, and so do not take a pattern from the original it self, but by an other pattern, representing the figure of the eye in a Looking-glass; The same doth the Ear, by patterning out Ecchoes, which is but a pattern of a pattern; But when as a man hears himself speak or make a sound, then the corporeal sensitive motions in the Ear, pattern out the object or figure made by the motions of the tongue and the throat, which is voice; By which we may observe, that there may be many figures made by several motions from one original; as for example, the figure of a word is made in a mans mouth, then the copy of that figure is made in the ear, then in the brain, and then in the memory, and all this in one Man: Also a word being made in a mans mouth, the air takes a copy or many copies thereof; but the Ear patterns them both out, first the original coming from the mouth, and then the copy made in the air, which is called an Eccho, and yet not any strikes or touches each others parts, onely perceives and patterns out each others figure. Neither are their substances the same, although the figures be alike; for the figure of a man may be carved in wood, then cut in brass, then in stone, and so forth, where the figure may be always the same, although the substances which do pattern out the figure are several, viz. Wood, Brass, Stone, &c. and so likewise may the figure of a stone be figured in the fleshy substance of the Eye, or the figure of light or colour, and yet the substance of the Eye remains full the same; neither doth the substantial figure of a stone, or tree, patterned out by the sensitive corporeal motions, in the flesh of an animal eye, change from being a vegetable or mineral, to an animal, and if this cannot be done by nature, much less by art; for if the figure of an animal be carved in wood or stone, it doth not give the wood or stone any animal knowledg, nor an animal substance, as flesh, bones, blood, &c. no more doth the patterning or figuring of a