IIAECKEL'S PHILOSOPHY. 411 



indeed, we can see the vibrating ether.* It is likewise a certain histor- 

 ical fact that man is descended from apes, etc.f The discovery of the 

 fossil ape-man of Java proves conclusively the descent of man from the 

 ape. X The existence of space and time is also definitely proved. The 

 historical evolution of the human soul from a long series of higher and 

 lower mammalian souls must be regarded as a scientifically proved 

 fact. 



We are now ready to take up HaeckePs metaphysics. We shall first 

 discuss the principles upon which his entire system rests and then con- 

 sider their application to inorganic nature, organic nature and the 

 psychical world. 



In the celebrated address which Du Bois-Eeymond delivered in the 

 year 1S80, and which was afterwards published as the ' Seven World 

 Biddies,' he proposed seven problems: (1) The essence of matter and 

 energy; (2) the origin of motion; (3) the origin of life; (4) the appar- 

 ently purposive arrangement of nature; (5) the origin of sensation and 

 consciousness ; ( 6 ) rational thought and the origin of language ; ( 7 ) the 

 question of free will. Questions 1, 2 and 5 he regards as impossible of 

 solution or transcendent; 3, 4 and 6 are difficult, but can be solved. 

 On question 7 he is undecided. Haeckel makes short work of these 

 riddles. The problem of matter and energy, the problem of motion 

 and the problem of consciousness are solved, he thinks, by his concep- 

 tion of substance; the problem of life, the teleological problem and 

 the problem of reason by the modern theory of evolution, while the 

 free will problem is no problem at all, but a dogma based on mere 

 illusion. 



The conception of substance is therefore Haeckel's fundamental 

 principle. Let us see what it means. There is one underlying prin- 

 are two different aspects.^ This substance is infinite, indestructible 

 and eternal; it fills the infinite space and is in eternal motion. The 

 matter and energy therefore in the universe are constant. This gives 

 us the laws of the conservation of matter and of energy, which really 

 form one single law, the law of substance, the cosmological ground law, 

 the law of the constancy of the universe, which follows necessarily from 

 the principle of causality. This universal substance reveals to us two 

 different aspects, two fundamental attributes: matter, the infinite 

 extended substance-stuff, and mind {Geist), the all-embracing sub- 

 stance-energy. It is God and nature at the same time ; body and mind 



* ' Monismus,' p. 16. 



f ' Weltraethsel,' p. 97. 



% P. 100. See also pp. 18, 73. 



I See ' Weltraethsel,' pp. 243fF. 



II P. 15. 



