 …in strict truth the ideas of sight, when we apprehend by them distance and things placed at a distance, do not suggest or mark out to us things actually existing at a distance, but only admonish us what ideas of touch will be imprinted in our minds at such and such distances of time, and in consequence of such or such actions. …[V]isible ideas are the language whereby the governing spirit … informs us what tangible ideas he is about to imprint upon us, in case we excite this or that motion in our own bodies.