Page:The Works of H G Wells Volume 11.pdf/219

 order to lead to my next question. One draws two lines strictly parallel; so

Oblique to them one draws a series of lines; so

and instantly the parallelism seems to be disturbed. If the second figure is presented to any one without sufficient science to understand this delusion, the impression is created that these lines converge to the right and diverge to the left. The vision is deceived in its mental factor and judges wrongly of the thing seen.

In this case we are able to measure the distance of the lines, to find how the main lines looked before the cross ones were drawn, to bring the deception up against fact of a different sort and so correct the mistake. If the ignorant observer were unable to do that, he might remain permanently under the impression that the main lines were out of parallelism. And all the infirmities of eye and ear, touch and taste, are discovered and checked by the fact that the erroneous impressions presently strike against fact and discover an incompatibility with it. If they did not we should never have discovered them. If