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and the acquirement begins. The two are joined at an 

 invisible line. For example, we cannot tell merely by exam- 

 ining an adult human limb which acquirements have been 

 made as a result of use. We know that the greater part of 

 its bulk is due to use only because we have previously learned 

 that human limbs develop very little after birth without that 

 stimulus. Precisely the same is true of mental characters. 

 The foal, for instance, is born with some instinctive know- 

 ledge 1 of how to co-ordinate its limbs for locomotion, avoid 

 obstacles, seek its mother's breast, and so forth. Experience 

 adds to this knowledge ; presently it learns better how to 

 co-ordinate its limbs, and avoid obstacles. Here again we 

 cannot distinguish the extension from the thing extended. 

 If a being, who had never before seen or heard of a man, 

 suddenly met one, he could not tell what part of the man's 



1 The use of the word knowledge with reference to the foal's instinct 

 may be thought objectionable. Some authors, apparently, would limit 

 the term to the products of experience garnered in the memory. There 

 is, however, plenty of warrant for its use in this connection. " Has the 

 bird a gland for the secretion of oil ? She knows how to press the oil 

 from the gland, and apply it to the feather. Has the rattle-snake the 

 grooved tooth and gland of poison 1 He knows without instruction 

 how to make both structure and function most effective against his 

 enemies. Has the silk-worm the function of secreting the fluid silk ? 

 At the proper time she winds the cocoon such as she has never seen, as 

 thousands before have done, and thus without instruction, pattern or 

 experience, forms a safe abode for herself in the period of transformation. 

 Has the hawk talons? She knows by instinct how to wield them 

 effectively against the helpless quarry." (A. Chadbourne, Instinct, 

 p. 28. Quoted by Professor W. James.) "The ichneumon which 

 deposits its eggs in the body of a larva hidden between the scales of fir- 

 cone, which it can never have seen, and yet knows where to seek." 

 (Romanes, Mental Evolution in Animals, p. 166.) 



Is it correct to say that a man " knows " how to walk 1 Yes. Then 

 it is certainly correct to say that the insect " knows" how to walk. The 

 man acquires through practice the ability to make the muscular 

 co-ordinations which result in walking, and this ability is what we term 

 " knowledge of hoiv to walk." In the insect the ability is inborn. One 

 class of stimuli develops it in man ; another class in the insect. The 

 final result is the same. The use of the word knowledge in this connec- 

 tion is sanctioned by universal custom ; but it must be remembered 

 that such knowledge differs very widely from that other kind of know- 

 ledge which can be represented in consciousness, and which the man 

 (especially the anatomist), but not the insect, can acquire the know- 

 ledge about walking. It should be noted that, in a sense, the insect is as 

 dependent on experience as the man. Unless he experiences a given 

 stimulus he does not walk. But experience in him merely awakens an 

 impulse ; it merely puts pre-existing machinery into action. In the 

 man it does more ; in part at least, it creates the machinery. The 

 experience does not add to the insect's knowledge, for it fades from his 

 mind immediately. It leaves its impress on the man's mind. 



