SCIENCE. 



[Vol. XXII. No 545 



"What shall be the means of checking them? Having said this, 

 they betojli themselves to meditation." 



They did not discuss questions of life and health only, but 

 moral and religious subjects also, and their effect upon life in 

 general. The wind, or breath, disorders of the billiary system 

 and phlegm, or improper secretions, seem to have been fully rec- 

 ognized as causes of bodily diseases, while passion and darkness 

 of mind brought about mental disorders. Long lists of drugs and 

 directions for their proper use are given, and there is abundant 

 evidence that the properties of vaccine matter were well known. 

 We are told that " He who knows how to apply these in disorders 

 is conversant with the science of medicine." And listen to the 

 following in regard to drugs and those who use them : " He who 

 is acquainted with their applications according to considerations 

 of time and place, after having observed their effects on individual 

 patients, should be known as the best of physicians. An un- 

 known drug is like poison, or weapon, or fire, or thunder, while a 

 known drug is like nectar. Drugs unknown by name, appearance, 

 and properties, or misapplied even if known, produce mischief. 

 Well applied, a virulent poison, even, may become an excellent 

 medicine, while a medicine misapplied becomes a virulent poison, 

 Only a physician who is possessed of memory, who is conversant 

 with causes and applications of drugs, who has his passions under 

 control, and who has quickness of decision, should, by the appli- 

 cation of drugs, treat diseases." 



Thirty-two kinds of powders and plasters and six hundred pur- 

 gatives are next described, after %vhich a chapter on food and its 

 proper use gives us as good advice as is to be found in any treatise 

 published in this learned nineteenth century. Great stress is laid 

 upon the proper care of the teeth, and a list of plants is given 

 from which brushes can be made, there not being manufactories 

 of such articles as there are now. 



" As the chief officer of a city protects hi* ci y, as the charioteer 

 protects his chariot, after the same manner should the intelligent 

 man be attentive to everything that should be done for the benefit 

 of his own body." Therefore, bodily, mental, and, if we may so 

 call it, religious hygiene is discussed at length, and many excellent 

 rules given. 



The question of the duality of the mind and of its connection 

 with the understanding and the soul leads us into all the intricate 

 mazes of Hindu phllorophy. but are here discussed in such a lucid 

 manner that one is not bewildered and can easily follow the line 

 of thought with pleasure and profit. 



••The objects of the mind are ideas. Here, again, the proper, 

 excessive, scant, and injudicious correlation of the mind with its 

 objects, or of the mental understanding with its objects, becomes 

 the cause of the normal or abnormal condition of oneself." In 

 other words, a man is sane or insane according to the proper or 

 improper agreement of the mind and its ideas, the ideas the un- 

 derstanding conceives; and, therefore, " One should act in such a 

 way as to preserve one's normal condition, in order that one's 

 untroubled senses and mind might continue in an untroubled 

 state; that is to say, by keeping oneself in touch with such ob- 

 jects of the senses as are productive of beneficial results; by prop- 

 erly achieving such acts as deserve to be achieved (and abstaining 

 from such acts as should be abstained from), repeatedly ascertain- 

 ing everything by a judicious e'jiployment of the understanding; 

 and, lastly, by resorting to practices that are opposed to the vir- 

 tues of the place of habitation, season of time, and one's own 

 particular nature or disposition (as dependant upon a preponder- 

 ance of this or that attribute or ingredient). Hence all persons 

 desirous of achieving their own good should always adopt with 

 heedfulness the practices of the good." 



Selfishness was never a cause of happiness, and we are told 

 '' one can never be happy by taking or enjoying anything alone 

 without dividing it with others." And this advice is good in every 

 age of the world — "one should not trust everybody, nor should 

 one mistrust everybody." 



Hindu works teach that everyone should have complete mastery 

 of his body and his senses, hence we frequently come across such 

 a sentence as this: " One should not suffer oneself to be overcome 

 by one's senses." 



A very interesting chapter is that which treats of '• The Aggre- 



gate of Four," that is, "the physician, nurse, drugs, and patient." 

 Each is considered and as good advice as can be found given for 

 the guidance of three of the aggregate. One thing, the first of 

 the four, is taught which it were well to remember in our day; 

 that is, that time must be considered in the treatment of all dis- 

 eases, and one must not try to force a cure. 



It would take more time and space than are at our disposal for 

 us to consider all of even the four parts of the Charaka that have 

 been published so far, but if any of our readers are interested, we 

 would be glad to give them any information in regard to the work 

 or the other publications of the learned editor of this great monu- 

 ment of ancient Hindu wisdom and leaaning. 



A NEW THEORY OF LIGHT SENSATION ' 



BY OBRISTINE LiDD FRANKLIN, JOHNS HOPKINS UNIVERSITY, 

 BALTIMORE, MD. 



The reasons which make it impossible for most people to ac- 

 cept either the Hering or the Young-Helmholtz theories of light 

 sensation are familiar to every one. The following are the most 

 important of them : 



The Young-Helmholtz theory requires us to believe: (a) some- 

 thing which is strongly contradicted by consciousness, viz., that 

 the sensation white is nothing but an even mixture of red-green- 

 blue sensations ; (6) son;ething which has a strong antecedent 

 improbability against it, viz., that under certain definite circum- 

 stances (e. g., for very excentric parts of the retina and for the 

 totally color-blind) all tbrie color-sensations are produced in ex- 

 actly their original integrity, but yet that they are never produced . 

 in any other than that even mixture which gives us the sensation 

 of white; (e) something wl ich is quantitatively quite impossible, 

 viz., ihat after-images, which are Irequently very brilliant, are 

 due to nothing but what is left over in the self-light of the retina 

 after part of it has been exhausted by fatigue, although we have 

 otherwise every reason to think that the whole of the self-light is 

 excessively faint. 



The theory of Hering avoids all of these difficulties of the 

 Young-HelmhoUz theory, but at the cost of introducing others 

 which are equally disagreeable; it sins against the first principles 

 of the physiologist by requiring us to think that the process of 

 building up highly organized animal tissue is useful in giving us 

 knowledge of the extei'nal world instead of supposing that it 

 takes place (as in every other instance known to us) simply for 

 the sake of its future useful tearing down; it necessarily brings 

 with it a quite hopeless confusion between our ideas of the bright- 

 ness and the relative whiteness of a given sensation (as is proved 

 by the fact that it enables Hering to rediscover, under the name 

 of the specific brightness of the different colors, a phenonrenon 

 which has long been i erfectly well known as the Purkinje phe- 

 nomenon^; the theory is contradicted (at least the present con- 

 ception of it) by the following fact — the white made out of red 

 and gi^een is not the same thing as the white made lut of blue 

 and yellow; for if (being mixed on the color-wheel) these two 

 whites are made equally bright at an ordinary intensity, they 

 will be found to be of very different brightness when the illumi- 

 nation is made very faint. 



Nevertheless, the theory of Hering would have to be accepted 

 if it were the only possible way of escape from the difficulties of 

 the Young-Helmholtz theory. But the>e difficulties may be 

 met by a theory which has the following for its principal assump- 

 tions. 



In its earliest stage of development vision consisted of nothing 

 but a sensation of grey (if we use the word grey to cover the 

 whole series black-grey- white). This sensation of grey was 

 brought about by the action upon the nerve-ends of a certain 

 chemical substance set free in the retina under the influence of 

 light. In the course of development of the visual sense the 

 molecule to be chemically decomposed became so differentiated 

 as to be capable of losing only a part of its exciting substance at 

 once; three chemical constituents of the exciter of the grey-sen- 

 sation can therefore now be present separately ("under the iiifluence 



'Abstract from the Proceedioga o£ the Internatloiial Congress o£ Experi- 

 mental Psychology, London, 1899. 



