Thus all evidence appears to conflict with the idea that the preferential employment of one hand can be accounted for by a mere general compliance with prevailing custom. Everywhere, in all ages, and in the most diverse conditions of civilised and savage life, the predominant usage is the same. Not that there are not everywhere marked exceptions to the prevailing practice, in left-handed athletes, handi-craftsmen, artificers, and artists, generally characterised by unusual dexterity; but the farther research is carried, it becomes the more apparent that these are exceptional deviations from the normal usage of humanity. CHAPTER IX PSYCHO-PHYSICAL ACTION The venerable philosopher of Chelsea, musing, with sorrowful experiences to stimulate inquisitiveness, after wondering if any people are to be found barbarous enough not to have this distinction of hands, sums up with the evasion: “Why that particular hand was chosen is a question not to be settled; not worth asking except as a kind of riddle.” It seems, however, to be regarded by intelligent inquirers as a riddle that ought to be, and that can be solved, though they have wandered into very diverse courses in search of a solution. It has been affirmed, for example, that while the right hand is more sensitive to touch, and, as it were, the special seat of the sense of feeling,--as with the right-handed it may well be from constant employment in all operations involving such a test,--the left hand is stated to be the more sensitive to any change of temperature. Mr. George Henry Lewes, in his _Physiology of Common Life_, says: “If the two hands be dipped in two basins of water at the same temperature, the left hand will feel the greater sensation of warmth; nay, it will do this even where the thermometers show that the water in the left basin is really somewhat colder than in the right basin;” and he adds: “I suspect that with ‘left-handed’ persons the reverse would be found.” On the assumption that the former is a well-established law, the latter seems a legitimate inference; but, as will be seen from what follows, there is good reason for doubting that the statement rests on an adequate amount of evidence.