Understanding human nature must be the basis of any real improvement in human life. Science has done wonders in mastering the laws of the physical world, but our own nature is much less understood, as yet, than the nature of stars and electrons. When science learns to understand human nature, it will be able to bring a happiness into our lives which machines and the physical sciences have failed to create.

Everything can be inherited except sterility. None of your direct ancestors died childless. Consequently, if we are to understand how human nature evolved, the very core of our inquiry must be reproduction, for reproductive success is the examination that all human genes must pass if they are not to be squeezed out by natural selection. Hence I am going to argue that there are very few features of the human psyche and nature that can be understand without reference to reproduction. I begin with sexuality itself.

When we study history we obtain a more profound insight into human nature by instituting a comparison between the present and former states of society.

The science of human nature belongs to people who are not afraid to live independent lives. They alone have the flexible access to experience which can bring human wisdom and strength into being, and once these assets exist, they will send forth their influence with an authority that cannot be resisted, unmindful of artificial man made boundaries, reaching anywhere in the world.

Like Wilson and a slew of other authors working on what was once called "sociobiology" but is now usually called "evolutionary behavior" or "evolutionary psychology," I am convinced that there is a biological and universal human nature, and that it appears manifest in the human record.The question is, how might that insight... be folded into the narratives that give our immediate history meaning and power?

There is not one human nature. There is not some uniform and unchanging way that everybody is and how everybody sees the world. Human nature has different meanings in different times and for different classes and groups in society.

No former age was ever in such a favorable position with regard to the sources of our knowledge of human nature. Psychology, ethnology, anthropology, and history have amassed an astonishingly rich and constantly increasing body of facts. Our technical instruments for observation and experimentation have been immensely improved, and our analyses have become sharper and more penetrating. We appear, nevertheless, not yet to have found a method for the mastery and organization of this material.... Unless we succeed in finding a clue of Ariadne to lead us out of this labyrinth, we can have no real insight into the general character of human culture; we shall remain lost in a mass of disconnected and disintegrated data which seem to lack all conceptual unity.

I am supposed to be a “nurturist” in the great “nature-nurture” debate, but I find nothing upsetting in this notion of biological influence upon human behavior. I suppose I must also emphasize once again, and for the umpteenth time as we all do, that the categories are absurd and that there is no “nature-nurture” debate as such, the pleasant alliteration of the phrase notwithstanding. Every scientist, indeed every intelligent person, knows that human social behavior is a complex and indivisible mix of biological and social influences. The issue is not whether nature or nurture determines human behavior, for these factors are truly inextricable, but the degree, intensity, and nature of the constraint exerted by biology upon the possible forms of social organization.

What we call human nature in actuality is human habit.

Go in confidence, study the rules, and above all things, study human nature for the proper study of mankind is man and you will find that while expanding the intellect and the muscles your enlarged experience will enable you to every day accumulate more and more principle which will increase itself by interest and otherwise until you arrive at a state of independence.

Fiction writing, for me, is also triggered by the drama of life I witness on daily basis. I find human nature an interesting study. Human relationships, especially romantic ones, are intriguing and highly fascinating.

You can’t study human nature in books. Books is a hindrance more than anything else. <small>p. 25</small>

Humanity is part of nature, a species that evolved among other species. The more closely we identify ourselves with the rest of life, the more quickly we will be able to discover the sources of human sensibility and acquire the knowledge on which an enduring ethic, a sense of preferred direction, can be built.

The view I have just sketched of the relationships between the most general types—the forms of social life—and human nature is based upon two key ideas that might appear contradictory. The first notion holds that there exists a limited fund of problems and possibilities of human association. Each form of social life is defined by the way it responds to the problems and pursues the possibilities. The fact that the fund is limited makes comprehensive theory and universal comparison possible. This principle, however, seems incompatible with the other half of my thesisː that the forms of social life are constituents and re-creators, rather than just examples, of human nature. ¶ The way to reconcile these two equally important ideas is to conceive of human nature as an entity embodied in particular forms of social life, though never exhausted by them. Consequently, humanity can always transcend any one of the kinds of society that develop it in a certain direction. Nonetheless, human nature is known, indeed it exists, only through the historical types of social life.