The Fallacies of Sight. [ 40]

THe Fallacy of the Sight is, when an Object is sometimes represented otherwise than really it is in it self; this ariseth sometimes from the vitiated Organ, as in those that are troubled with the Jaundice, or from that defect of the Medium; as if Snow be seen through a Red Glass, it appears otherwise than what it is in it self.

There is also a Fallacy of Sight arising from Distance, when by reason of overmuch Distance those Things which are really bigger, appear less; and long Walks appear narrower and nar∣rower from the beginning towards the end. Moreover, Sight fails as to the Figure, as when a Circle plac'd obliquely appears like an Ellipsis; because the Species proceeding from thence by reason of the obliquity of the Situation is more contracted on one side, and so represents the Image of the Circle as it is.

Lastly, There is a Fallacy as to Motion; as when to those that Sail, the Shoars seem to move, and Cities seem to go back, when indeed 'tis the Ship that moves.

All Fallacies in the Act of Beholding, arise from the short-sightedness of the Beholder; as when there appears but a Foot in Diameter, when as it is a Magnitude infinitely bigger. Or from a false Estimation; as when any one beholding a Fire afar off, thinks it to be a Star: Or from a Paralogism, as when that Motion is imputed to the Moon, which is really in the Clouds.

Sometimes the Error is only in the Mind, either wavering in doubtful things, or moved by a contrary Affection; or by Phrensie justled from its proper Seat, or for want of serious Atten∣tion.

These Errors may be corrected as well by the Mind, as by other inward and outward Senses; as when the Touch finds that to be plain in Picture, which to the Eye seems prominent, or jutting out; and the Vnderstanding corrects the erring Faculty, and it self, when the cause of the Error is taken away, and so as well the in∣ternal, as the external Senses, have such a con∣nexion with the Intellect, as to contribute mutual assistance to each other. Who desires to see these things more fully discust, let him consult Vitelle, and Aguilonius.