1 10 Mind obeys the principle of Heredity. 



living bone transplanted to fleshy parts of animals 

 where there was no bone, continued to grow for a 

 time by a life of their own, and increased by forma- 

 tion of additional bone, like a crystal grows in its 

 medium ; but after a time they diminished and disap- 

 peared. In a similar manner we are all of us aware 

 of the persistency of ideas, even in opposition to the 

 will, after the cause of them has been removed. 

 Sometimes we cannot retain an idea because of the 

 persistence of others ; and at other times we cannot 

 .get rid of one, for a similar reason. Our mental 

 habits also have often very great persistence. 



The principle of heredity may be viewed as a 

 result of the First law of Motion, and appears as Per- 

 sistency of state, either of structure, form, or mode of 

 action. It appears both in inanimate bodies, living 

 structures, and in mental phenomena; in the latter, as 

 hereditary mental peculiarities. The principle of Per- 

 sistency of structure and Heredity of form and 

 property, during repeated or even continual dissolu- 

 tion and aggregation of a material substance, is more 

 or less manifest nearly throughout the whole of 

 nature. In the formation of crystals it is clearly 

 seen ; each crystallizable substance will only grow 

 into its own shape or shapes ; each particle of com- 

 mon salt, during an endless series of successive 

 solutions and aggregations into the solid state, always 

 forms a more or less perfect cube ; that of silica a 

 hexagon ; and so on throughout the entire series of 

 thousands of different crystalline bodies. As each 



