Many of these sciences relate to our social condition. And of these the importance and value every day rapidly increases. Good government largely depends upon knowledge of all those natural laws upon which moral and physical well-being depends. Upon good government follow increased wealth, active trade, higher wages, and larger consumption of commodities. Upon these follows increased population, and that population concentrated upon spots favourable for all this activity. And upon this follow new social difficulties; fresh problems arise to be solved, and new questions to occupy the mind both of the student and of the statesman. Unless solved, society will retrograde; it will suffer in health, in wealth, and morality; turbulence will take the place of quiet industry; and that community will decay. Here again nature provides a field for the employment of our faculties, and compels us to use them. If not there is the same penalty, degradation. I do not know how many geological periods it would take before, by the neglect of our powers, we could retrograde back to our ascidian progenitor; but I see everywhere around me the proofs that retrogression is as much a law of man's nature as progress. We can only continue what we are by using all our powers.[27] But I may have lingered over this part of my subject too long. No one perhaps will deny that man both can and must use his mental powers as thoroughly as an animal must use its instincts, and a plant its vegetative powers, or it will suffer for its neglect. Only remember that my argument has nothing to do with individuals; I am treating of man as a species, and investigating the general laws which regulate his well being. Well, now, has man any other powers than those already described? Has he merely physical powers to enable him to get food, and other bodily necessaries; and mental powers to enable him to read, write, and cypher? Is this all? You know that it is not all. There is another broad distinction between man and all the other inhabitants of this earth. He alone distinguishes between right and wrong.[28]