Our present-day knowledge prompts the adoption of a middle course between the two theories.
In his view, Nature has made provision for social wellbeing by the principle of the human constitution which prompts every man to better his condition: the individual aims only at his private gain, but is "led by an invisible hand" to promote the public good; human institutions, by interfering with this principle in the name of the public interest, defeat their own end; but, when all systems of preference or restraint are taken away, "the obvious and simple system of natural liberty establishes itself of its own accord."
It may be affection, or it may be fear, which prompts the survivor to feed and tend his dead; in general no doubt it is a mixture of both feelings.
ALASTOR, in Greek mythology, the spirit of revenge, which prompts the members of a family to commit fresh crimes to obtain satisfaction.
To this extent monism is justified; but it becomes mischievous if it prompts us to ignore important differences in facts as they present themselves to our intelligence.