A short demonstration Neville runs in front of an audience to prove that imagining is sensation and not fantasy. He imagines a ball where there is none and feels it; then, with the same hand, a piece of silk; then something steel. The question put to the listener is not whether the objects are there but whether the feels are different - and they are: no one confuses the baseball with the tennis ball, or either with the mohair. The inference is then pressed as a piece of logic: if I can discriminate between these imaginal objects then they exist, because you cannot discriminate between that which does not exist; where there is nothing there is no distinction and no discrimination. The instrument list varies - baseball, tennis ball, billiard ball, piece of silk, piece of mohair, a bat, the hand of a child, the hand of a wife or husband (1050, 1216, 1298) - and at 1050 it is put to immediate use, the imaginary thumb placed on the wedding ring that is not there. It is a child of the Blake letter (M574): where that motif states that imagination is spiritual sensation, this one is the proof offered for it, and the proof is an argument from discrimination rather than an appeal to vividness.