192 The Eiwlution of Mind. 



musoles are in physical work. As a man's power to execute 

 the decrees of his will on brute nature varies with his mus- 

 euLir power, so does his power to concentrate his attention, 

 and think, vary in proportion to the size of his frontal lobes. 

 We found elsewhere how the mind obeyed the law of evo- 

 lution by increasing its correspondence Avith objective facts 

 in time, in space, in heterogenity, in speciality and in gen- 

 erality. Here Ave discover how it intensifies its activity and 

 reaches toward more and more rapid strides in all these 

 directions by the growth of the poAver of attention. 



At the very base of its career this poAver must have been 

 present. As Professor Cope has said, "Physical and men- 

 tal development depend on the Avill."* To knoAv, requires 

 prolonged experience.! In the rushing stream of Time, 

 what we call Now is but ati imaginary line ending the past 

 and A^erging on the futvire. To know, includes the past. 

 The absolute present Avithout it is nothing. To embrace 

 the past in knowledge is to remember, but it is also to use 

 attention. Given attention and retained experiences, and 

 Ave have awareness or consciousness. It may be the lowest 

 type of consciousness, knoAvn to us as simple feeling. Will, 

 memory and feeling are thus seen to constitute the indivisi- 

 ble psychic trinity. IMatter has a similar trinity in its 

 length, breadth and depth. The evolution of all material 

 forms came by adding atom to atom in three dimensions. 

 The evolution of mentality came by somehoAV making it 

 possible to expand its three dimensions of feeling, memorj* 

 or intellect, and Avill.| How the first of the three grcAv 

 into its heterogeneity of color and sound, taste and smell, 

 heat and cold, is an unsolvable problem. We knoAv that 

 the difference between the objective causes of yelloAV and 

 red is speed of vibration. § AVe do not and probably ncA'er 

 will know how the sensation red changes into the sensation 

 green. The same is true of all other sensations. iSTo theory 

 can be framed that will enable us to assimilate them. We 

 may yet by successive analyses discover the psychic steps 

 through Avhich we reached up from the lower to the higher, 

 but farther than this Ave cannot hope to traA'el. 



That a distinct unity of composition exists betAveen all 

 our mental states is the positiA^e implication of evolution. 



* American Naturalist, Vol. 21, p. 1128. 

 t Kibot's Diseases of Memory, p. 34. 

 i Bain's Mind and Body, pj). "4:i, 44. 

 § Lomell's Nature of Light, p. 226. 



