382 Appendix 
“creates a current of affection because of services ren- 
dered.” 27 
“Every one recognizes,” says Pillon in his turn, “that 
the love of parents for their children exceeds in intensity 
the children’s love for the parents, and that of the two 
parents it is the mother whose love is stronger for her 
child. . . . The reason is that in the mother’s case much 
more than with the father the love for the child is nour- 
ished and stimulated, because of her special functions, 
that is, by the constant performance of the actions it 
dictates.” 28 
But mother-love and mutual love within the family in 
general, owing its origin to certain relations grown into 
habit, represents only one particular case of a universal 
law. For every other relation to person or things (no 
matter how special) which becomes in the slightest 
degree a habit finally appears for this very reason as 
something “desired.” In every environmental relation 
whether general or particular is verified Lehmann’s law 
of the “‘indispensability of the customary,” which this in- 
vestigator established for every stimulus to which one 
becomes accustomed and whose cessation arouses a need 
for its presence.” 
“T have a small clock in my room,” a friend once 
wrote to G. E. Miller, “which will not run quite twenty- 
four hours with one winding. It often happens therefore 
that it stops. Whenever this occurs I notice it at once, 
whereas of course I do not hear it at all when it is 
27Ribot, Psych. des sent., p. 286. 
28F, Pillon, “Sur la mémoire et l’imagination affective,’ Année 
vhilosophique, XVII, 1903, pp. 69-70. Paris, Alcan, 1907. 
#94. Lehmann, Die Hauptgesetze des menschlichen Gefiihlslebens, 
pp. 194 ff. Leipsic, Reisland, 1892. 
