Nevertheless, Hartmann and his followers do not on this account hesitate to ascribe true intelligence to unconscious nature, and though such ascription may seem too absurd to deserve serious consideration, it would nevertheless be a great mistake to despise such opinions. For, as Mr. Lewes truly says,[34] “As there are many truths which cease to be appreciated because they are never disputed,” so there are many errors which are best exposed by allowing them to run to a head. Mr. Butler, who carries this hypothesis of unconscious intelligence to its last consequences, asks,[35] “What is to know how to do a thing?” His answer is, “Surely, to do it.” And he represents how, when many things have been perfectly learnt, they may be performed unconsciously. In a very amusing chapter on “Conscious and unconscious knowers,” he says, “Whenever we find people knowing they know this or that ... they do not yet know it perfectly.” In another place he says,[36] “We say of the chicken that it knows how to run about as soon as it is hatched ... but had it no knowledge before it was hatched? It grew eyes, feathers, and bones; yet we say it knew nothing about all this.... What, then, does it know? Whatever it knows so well as to be unconscious of knowing it. Knowledge dwells on the confines of uncertainty. When we are very certain we do not know that we know. When we will very strongly, we do not know that we will.” [34] _Problems of Life and Mind_, ii. iii. iv. of Third Series, p. 85. [35] _Life and Habit_, p. 55. [36] _Unconscious Memory_, p. 30. Now the fact is that there is great ambiguity in the use of the word _know_. Just as before with the term memory, so also here, certain distinctions must be drawn if we would think coherently. A. To “know,” in the highest sense which we give to the word, is to be aware (by a reflex act) that we really have a certain given perception. It is a voluntary, intelligent, self-conscious act, parallel to that kind of memory which we before distinguished as “recollection.” B. We also say we “know” when we do not use a reflex act, but yet have a true perception—a perception accompanied by consciousness—as when we teach, and in most of our ordinary intellectual acts.