224 (I0> 



probably by machinery of which no record remains. 

 We picture to ourselves the swarming workers toiling at 

 those vast erections, lifting the inert stones, and, guided 

 by the volition, the skill, and possibly at times by the 

 whip of the architect, placing the stones in their proper 

 positions. The blocks in this case were moved by a 

 power external to themselves, and the final form of the 

 pyramid expressed the thought of its human builder. 



Let us pass from this illustration of building power to 

 another of a different kind. When a solution of com- 

 mon salt is slowly evaporated, the water which holds the 

 salt in solution disappears, but the salt itself remains 

 behind. At a certain stage of concentration, the salt 

 can no longer retain the liquid form ; its particles, or 

 molecules, as they are called, begin to deposit them- 

 selves as minute solids, so minute, indeed, as to defy all 

 microscopic power. As evaporation continues solidifi- 

 cation goes on, and we finally obtain, through the clus- 

 tering together of innumerable molecules, a finite mass 

 of salt of a definite form. What is this form ? It some- 

 times seems a mimicry of the architecture of Egypt. 

 We have little pyramids built by the salt, terrace above 

 terrace from ba^se to apex, forming thus a series of steps 

 resembling those up which the Egyptian traveler is 

 dragged by his guides. The human mind is as little dis- 

 posed to look at these pyramidal salt-crystals without 

 further question as to look at the pyramids of Egypt 

 without inquiring whence they came. How, then, are 

 those salt pyramids built up ? 



Guided by analogy, you may suppose that, swarming 

 among the constituent molecules of the salt, there is an 

 invisible population, guided and coerced by some invis- 

 ible master, and placing the ajtomic_blqcks in their posi- 



