■L-JO THE HISTORY OF BIOLOGY 



and throughout his life he retained his interest in natural research, not 

 least in biology. His first papers, in fact, dealt with mechanical and cos- 

 mological problems; the best known of these is his Allgememe Naturge- 

 schkhte und Theorie des Himmels, in which he tried to set up a mechanical 

 theory concerning the origin of the universe. On this subject Swedenborg 

 and BufFon had been his precursors; BufFon, an account of whose cosmological 

 theory has been given above, seems to have been his chief source of inspira- 

 tion. In contrast to the latter, Kant believes that the planetary system has 

 evolved from a collection of dust particles which moved in space and even- 

 tually became concentrated. This theory, the details of which need not be 

 recounted here, all the more so as it has often been referred to, testifies to 

 Kant's efforts to find a mechanical explanation of existence. Towards the 

 end of the work, however, he becomes involved, doubtless under the in- 

 fluence of Swedenborg, in fantastic speculations about life on other heavenly 

 bodies; he believes that on the more distant planets, Jupiter and Saturn, 

 there are beings of a higher order of intelligence than that of man — this 

 because the inhabitants of the more distant planets must be made of lighter 

 material in order that the less intense solar heat there may set them in mo- 

 tion; but the lighter the corporeal matter the greater the intelligence, while 

 heavy bodily fibres and dense, "sluggishly cooking" fluids result in in- 

 ferior abilities. Strangest of all, he cites Newton's calculations in support 

 of this theory, which might more naturally have originated from the earliest 

 Greek philosophers. Kant, however, soon rose above these fantasies; in a 

 paper published ten years later entitled Trdume eines Geistersehers he settles 

 with Swedenborg, as indeed with all metaphysical speculations upon the 

 relation between spirit and matter. He ironically examines all the old theories 

 about the location of the soul — now existing everywhere in the body, now 

 located in a small section of the brain — and finally proves the impossibility 

 of determining how the soul influences the body or whether spiritual beings 

 can exist without material space; reason is as little able to decide this ques- 

 tion as it is to determine how anything can be a cause or can possess a force — 

 which are all matters that can only be determined by experience; and alleged 

 experiences of single individuals, such as Swedenborg's visions, cannot form 

 the basis of a law of experience for the very reason that they are isolated 

 cases. He ends by pointing out that there certainly are many things that we 

 do not understand, but there is also a very great deal that we do not need 

 to understand. We must be quite clear as to what is necessary for us to know 

 and what in that respect can and must be dispensed with. 



Kant, having thus exposed the futility of the old metaphysical specula- 

 tions, spent more than ten years in trying to find out the limitations and 

 conditions of the human capacity for knowledge in general. The result of 

 these researches he recorded in his Kritik der reinen Vernunjt, published in 



