Page:Philosophical Transactions - Volume 013.djvu/188

 impression. Besides to answer one similitude with another, we may observe that the Fibres of those Muscles that extend the leg, and bear-upon the bow of the knee, seem more strecht and vigorous in their action then the contractors that run in the hollow under it; and this was admirably contriv'd by the Wisdom of our great Author (and may be unanswerably objected to the followers of Epicurus, who say the parts of the human body were made without any design:) for since those Extending Muscles of our leggs are much pent up and hindred in their action by the posture of the Child in the Womb (which lies with its knees up to its mouth,) that defect is excellently compensated by the natural tension and position of the said Fibres, or else Man could never go upright.

6. It has been urg'd That the action of Vision was uniform, and therefore requir'd an uniform tension of all the Fibres. To which I answer, that tho in the view of the intire object, or its place lay both eyes, it ought to be so, and that therefore it was done by correspondent Fibres (as I have formerly explain'd); yet in a stricter view of the parts of the same Object by one Eye, there is a discrimination. For to instance in a body of the most simple figure and colour, (as suppose a Globe all red, or of Fire) that should be seen by one Eye only, 'tis certain the Eye distinguishes the different parts in their extra positions, or distinct situations in respect of one another, tho they be all of a piece as it were otherwise: and unless it were so, I see no reason why that red Globe should not appear only one red speck, Or a Globe of fire as a lucid point: Now this distinguishing of the parts is easily conceivable to be done by the discord Fibres of the same Eye.

7. Lately it has been urg'd That the Fibres of the Choroeides seem more adapted to Vision then those of the Retina, because these last did not sistere species (to use their phrase) as transmitting the colours of the former; and besides some Blood-vessels running amongst 'em would interrupt the