Except so far as there may have been direct communications from the Supreme Being, all *man’s knowledge* of persons, objects, and relations *is derived*, in the last resort, *from observation*. Experience is merely remembered self-observation. Tradition, oral and written, is accumulated and condensed observation; and by means of this each new generation can avail itself of the experience of preceding generations, can thus find time to explore fresh departments of knowledge, and so transmit its own traditions to the generations that shall follow. Now what we observe in objects is chiefly their properties, or, what is the same thing, their _fitnesses_; for a property is that which fits an object for a specific place or use. What we observe in persons is their relations to other beings and objects, with the fitnesses that belong to those relations. What we experience all resolves itself into the fitness or unfitness of persons and objects to one *another* or to ourselves. What is transmitted in history and in science is the record of fitnesses or unfitnesses that have been ascertained by observation, or tested by experience. The progress of knowledge is simply an enlarged acquaintance with the fitnesses of persons and things. He knows the most, who most fully comprehends the relations in which the beings and objects in the universe stand, have stood, and ought to stand toward one another. Moreover, as when we see a fitness within our sphere of action, we perceive intuitively that it is right to respect it, wrong to violate it, our knowledge of right and wrong is co-extensive with our knowledge of persons and things. The more enlightened and cultivated a nation is, then, the more does it know as to right and wrong, whatever may be its standard of practical morality. For instance, in the most savage condition, men know, with reference to certain articles of *food and drink*, that they are adapted to relieve the cravings of hunger and thirst, and they know nothing more about them. They are not acquainted with the laws of health, whether of body or of mind. They therefore eat and drink whatever comes to hand, without imagining the possibility of wrong-doing in this matter. But, with the progress of civilization, they learn that various kinds of food and drink impair the health, cloud the brain, enfeeble the working power, and therefore are unfit for human use; and no sooner is this known, than the distinction of right and wrong begins to be recognized, as to what men eat and drink. The more thorough is the knowledge of the human body and of the action of various substances on its organs and tissues, the more minute and discriminating will be the perception of fitness or unfitness as to the objects that tempt the appetites, and the keener will be the sense of right or wrong in their use.