As a boy, I heard my father recount a lesson he had once learned in college. As I look back, that lesson had an impact on my own thinking. It went something like this.

Imagine yourself at the end of the universe, wherever that happens to be. You have a ball in your hand. Throw the ball toward the end of the universe. If it continues flying forward, you obviously haven’t reached the end of the universe. If on the other hand the ball bounces back to you, you can ask about what lies beyond the end of the universe -- on the other side of that wall, as it were. Whatever it is, it belongs as much to the universe as anything else, which means that on the other side the universe continues and, once again, you haven’t reached the end of the universe.

The point I wish to make is not about the physical or logical solution to that paradox. Rather, I am introducing a kind of archetypal awareness that has since shaped my own thinking about the relationship of what lies before you with what lies beyond.

Philosophers have wrestled with this problem of surface and depth since the beginning. Thales held that the world is full of gods. Obviously, you cannot see them, but he assured us they are there. Other Greek philosophers attempted to give their own explanations, about how a world filled with so many different things is comprised of only four elements or of tiny atoms. Heraclitus wrote about a hidden reality that is more than we can hope to understand. Plato developed an elaborate theory distinguishing a realm of appearances, on the one hand, with a realm of forms, on the other. Much, much later Immanuel Kant made the distinction fundamental to the rest of his thinking between phenomena we experience through our senses and things-in-themselves. He wrote in The Critique of Pure Reason that “though we cannot know these objects as things in themselves, we must yet be in a position at least to think them as things in themselves; otherwise we should be landed in the absurd conclusion that there can be appearance without anything that appears."

Plato’s Forms are not the same as Kant’s things-in-themselves. Nevertheless, they stand in an equivalent position to the world of direct experience: that is, they symbolize something about what might lie beyond direct experience.

We cannot function in ordinary life after a certain point without some awareness that a world lies beyond direct experience. The infant cries in part to summon help from a person no longer present. The student opens the school house door on the assumption that a classroom waits on the other side. I infer the existence of a heart in my own chest, based in part on what I have seen in diagrams from textbooks, but also as a logical inference about the way my blood circulates. Something does that work. Besides, I can actually hear it, even if I cannot see it.

In everyday experience, we encounter physical surfaces like a drapery over the rest of the world. We touch an orange rind and presuppose the fruit inside. We pick up a book in order to read something in its pages. Somebody leaves the room, and we do not assume she immediately ceases to exist. In fact, our folk wisdom is often based on the perils of making inferences about the world beyond direct experience, inasmuch as “you can’t judge a book by its cover” and “all that glitters is not gold” and “look before you leap”.

I recall there was once a warning for automobile drivers not to assume that a paper sack in the road is empty. Driving over it is also driving over its contents, such as a broken bottle that might puncture your tires.

Scientists have taken the distinction between surfaces and depth to heart and resolved to penetrate surfaces, to find out how it all really works. On a map of the globe from the 1500’s, an unexplored region bore this inscription, “Here there be monsters.” The universe presents the curious with boundless opportunity to probe and peer – to cut open the skin, to dive into the sea, to watch the microbes dance, and to witness stars being born. And with the accumulation of knowledge, humans win an increasingly rich understanding of a reality that otherwise eludes our native powers.

The culmination of my training was law school, when the objective was to operate in a climate of skepticism and doubt. What exactly are the facts of the case? What can we infer from those facts? What can we prove? And what is the legal significance of these things? For it is there, in that adversative system, that whatever you take to be the case will be contested and judged by somebody else, and you have to be ready for that. Thus, you have to open your mind repeatedly to the possibility that you are mistaken or that your client is mistaken or that a witness is mistaken or that a judge is mistaken. Perhaps I chose to study the law because it offered such a vigorous bath for my mind and left me wary of all seeming.

Yet all along the way, I never forgot episodes in my life when I misjudged people and discovered they had lied to me or betrayed me or harbored grievances against me. A man learns from these mistakes and gradually makes himself less vulnerable to them – perhaps by avoiding people altogether or perhaps by regarding other people with suspicion. “Fool me once, shame on you. Fool me twice, shame on me.” It takes a person who is either very strong or very stupid to remain vulnerable and expose himself again and again to the risk of being wrong. It takes a whole mountain to forgive. In brief, you don’t need a law degree to develop a wary disposition.

Ultimately, a life spent distrusting the evidence, vigilant against unforeseen hazards, forever at play in the mind imagining the world this way and that, facile with theory and fearful of fact -- such a life reduces to anxiety, both as pathology and dysfunction, or it escapes into madness, like a spaceship free from earth's gravity and floating easily in a cold and colorless vacuum that has no end.