But are we at the end? Should we not say something about =inattention=, which in everyday life we take to be the opposite of attention? have we not still to describe the inattentive state? No: _in the normal waking life there is, in strictness, no such thing as inattention_. We give that name to an attention which is directed upon what we regard as an improper object. The inattentive person is merely attending to something else; the pattern remains the same. It is possible that, in certain abnormal cases, all mental processes alike run their course in relative obscurity; but even here we are not dealing with inattention; there is some weakness or obstruction of nerve-forces, which prevents sensations from reaching their full normal vividness. § 22. =The Experimental Study of Attention.=—The question of the =range= of attention,—how many sensations or images may occupy the focus at the same time,—was canvassed in the Middle Ages: witness our quotation from St. Thomas. The first appeal to experiment seems to have been made, in the late thirties of the past century, by the Scottish philosopher Sir Wm. Hamilton. “You can easily make the experiment for yourselves,” Hamilton tells his students, “but you must beware of grouping the objects into classes. If you throw a handful of marbles on the floor, you will find it difficult to view at once more than six, or seven at most, without confusion; but if you group them into twos, or threes, or fives, you can comprehend as many groups as you can units.” The experiment is not very rigorous; but more accurate work on the subject shows that Hamilton was not far wrong. _If a field of simple visual stimuli is shown for a brief time, the practised observer is in fact able to grasp six of them_; and if familiar groups are substituted for the separate stimuli (short words for letters, or playing-card fives for single dots), the range of visual attention remains the same.