But given the practice or experience, and the intricacy of the process to be performed appears to matter very little. There is hardly anything conceivable as being done by man, which a certain amount of familiarity will not enable him to do, as it were mechanically and without conscious effort. “The most complex and difficult movements,” writes Mr Darwin, “can in time be performed without the least effort or consciousness.” All the main business of life is done thus unconsciously or semi-unconsciously. For what is the main business of life? We work that we may eat and digest, rather than eat and digest that we may work; this, at any rate, is the normal state of things: the more important business then is that which is carried on unconsciously. So again the action of the brain, which goes on prior to our realising the idea in which it results, is not perceived by the individual. So also all the deeper springs of action and conviction. The residuum with which we fret and worry ourselves is a mere matter of detail, as the higgling and haggling of the market, which is not over the bulk of the price, but over the last halfpenny. Shall we say, then, that a baby of a day old sucks (which involves the whole principle of the pump, and hence a profound practical knowledge of the laws of pneumatics and hydrostatics), digests, oxygenises its blood (millions of years before Sir Humphry Davy discovered oxygen), sees and hears—all most difficult and complicated operations, involving a knowledge of the facts concerning optics and acoustics, compared with which the discoveries of Newton sink into utter insignificance? Shall we say that a baby can do all these things at once, doing them so well and so regularly, without being even able to direct its attention to them, and without mistake, and at the same time not know how to do them, and never have done them before? Such an assertion would be a contradiction to the whole experience of mankind. Surely the _onus probandi_ must rest with him who makes it.