516 



experience, he is not adaptable ; he moves in much 

 the same groove as did his ancestors of a milUon 

 years ago. 



Higher than the caterpillar in the animal scale, the 

 power of growing mentally in response to functional 

 activity is clearly in being. Animals are able to 

 recognise mates and offspring, and the latter are able 

 to recognise their guardians. Family life begins. 

 The offspring, more or less helpless at birth, but 

 protected by their guardians, have ability and oppor- 

 tunity to develop physically and mentally in response 

 to functional activity until they are able to fend for 

 themselves. They begin to think, they become 

 adaptable. This evolution culminates in man, who 

 is born so helpless that he cannot even seek the 

 breast, but who learns so enormously that he becomes 

 rational. Reason is merely intelligence in excelsis. A 

 vast and complex store of experience then lights a 

 complex, and perhaps distant, future. Compare 

 three human individuals — an idiot, a newly born 

 baby, and a normal man. The idiot cannot learn, 

 and has not learned ; the baby can learn, but has not 

 learned ; the normal man can learn, and has learned. 

 There in a nutshell is all the mental difference between 

 them, except that the baby has not yet developed 

 a few instincts. The idiot has these instincts, but, 

 probably because he has lacked some hormone, has 

 reverted by mutation (himself or by some progenitor) 

 to an enormously remote ancestry in which the power 

 of learning was defective. One day I think we shall 

 cure idiocy by the injection of the proper glandular 

 extract. Compare a man with a dog : how enor- 

 mously greater is the human power of learning, and, 

 therefore, of thinking. Compare him with a house- 

 fly : the fly settles on the hand ; we strike at it ; 

 impelled by instinct, it shoots away ; a moment 

 after, having ceased to " bear in mind," it is back 

 again, unmindful of a danger the recollection of which 

 would set a man shuddering for years. We are able 

 to domesticate animals only when they have the 

 capacity to learn to tolerate, to obey, and, when the 

 intelligence is very great {e.g. dog), even to love us. 

 Savage man is so intelligent that he has invented 

 language by means of which he is able to hand on the 

 accumulated traditions of generations. Civilised man 

 differs from him in that he has invented aids to his powers 

 of remembering {e.g. books of reference), of thinking 

 {e.g. mathematics), and of doing {e.g. tools). The 

 retrogression of instinct and its replacement by intelli- 

 gence is well illustrated by maternal care among 

 brutes and men. Among the former it is instinctive, 

 but women have to learn how to tend their young. 

 Again, while insects walk instinctively, men learn. 

 Among the higher animals the number of offspring 

 is controlled by the number which can be protected 

 and taught. 



This or that naturalist may disagree as to this or 

 that detail of what I have written about mind, 

 but with the main argument I think all must agree. 

 Already, in practice if not in theory, actions which 

 are not initiated by the will are called reflex ; those 

 which are initiated by the will, but in which learning 

 plays no part, are called instinctive ; while those 

 which are both initiated by the will and result from 

 learning are called intelligent. As to the evolution 

 of the potentiality of developing in response to use, 

 the truth is glaringly obvious. Even a schoolboy 

 knows that he can teach a beetle nothing, a cat a 

 little, a dog more, and a child much. But all this is 

 incompatible with Lamarck's first law, which has 

 met with such general acceptance. As regards body, 

 the evolution may be more difficult to trace. At any 

 rate, it has not been studied. But as regards mind 

 it is as clear as sunlight. Plainly, an animal is in- 

 telligent in proportion as it is able to profit from 



NO. 2738, VOL. 109] 



NATURE [April 22, 1922 



experience ; man's reason and intellect depend wholly 

 on his power of learning ; and, as well as I can judge, 

 whenever an animal is capable of learning it is also 

 capable of developing physically in a corresponding 

 degree in response to the stimulus of use. 



G. Archdall Reid. 

 9 Victoria Road South, Southsea, Hants. 



Pencil Markings in the Bodleian Library. 



In a former communication (Nature, 1920, vol. 

 105, p. 12) I described a method of distinguishing 

 microscopically between the markings made upon 

 paper with different kinds of pencils, and gave some 

 account of the characteristics of early pencil writings 

 in the British Museum. 



I am now indebted to the Librarian of the Bodleian 

 Library and to Dr. Craster for their kindness in 

 giving me facilities for studying .similar early specimens 

 of pencil writing in that library. 



In Schonemann's work on the examination of 

 early MSS. (" Versuch eines Systems der Diplo- 

 matik," 1818, vol. ii. p. 108) it is stated that the 

 ruled lines in various documents of the eleventh and 

 twelfth centuries are in a graphite pigment. Refer- 

 ring to this statement I pointed out {loc. cit.) that, 

 since graphite was only discovered in 1560, it was 

 obvious that Schonemann must have mistaken 

 ordinary metallic lead for graphite. 



The historical basis for my criticism is to be found 

 in Gesner's " De Rerum Fossilium Lapidum et 

 Gemmarum Genere," 1565, vol. ii. p. 105, and in 

 Beckmann's " Beitrage zur Geschichte der Erfin- 

 dungen " (1780). It appears, however, that graphite 

 must have been known long before that time, for, 

 after reading my communication. Prof. Flinders 

 Petrie informed me that he had discovered a lump 

 of graphite at Ghorub, which must have dated back 

 to a period between 1500 and 1200 B.C., although 

 there was no evidence that graphite was ever used 

 as a pigment in ancient Egypt. 



This unique specimen of graphite, a portion of 

 which Prof. Flinders Petrie has kindly given me for 

 examination, is a decidedly coarse, impure mineral, 

 containing only 39-4 per cent, of carbon, and the 

 amount of silicious impurities present is plainly 

 indicated by the pronounced irregular striations in 

 the markings on paper. 



This proof that graphite was known ages before 

 its reputed discovery in 1560 in the Borrowdale mine, 

 gives an added interest to the examination of the 

 earliest pencil markings available in this country. 



The earliest known instance of pencil marking in 

 the Bodleian is a vellum MS. Commentary on the 

 Book of Job of the thirteenth century (Auct. D. iii. 14). 

 This has vertical lines, ruled with a stylus down the 

 sides of the writing, and the microscope shows that 

 the pigment of these is lead or other metal. 



In the " Opuscula Varia SS. Augustini et Bernardi" 

 of the thirteenth and fourteenth centuries (Hatton 

 MS. 102), the ruled lines surrounding the text are in 

 a red ink in some of the MSS., whilst in others they 

 are in a metallic pigment. In another Hatton MS. 

 (No. 107) of the fourteenth century, no pencil mark- 

 ings are present, the ruled lines at the side and the 

 annotations being in a pale brown ink. 



The "Opera Johannis Dastyn " of 1590 (Bodl. MS. 

 485) is written in ink, and shows pencil strokes 

 at the side written in graphite, but there is no 

 evidence that these markings were contemporaneous 

 with the body of the MS. 



An Italian MS. on paper, " Geomantia " (Digby 

 MS. 133), written in ink prior to 1634, shows fine 

 ruled lines at the side in a brilliant metallic pigment ; 



