The world smiled a wry, weary smile and said, "Nice work, son. Now sit down and let me teach you the rest of the alphabet. Plan on it taking a lifetime."

It is not a coincidence that graduation ceremonies are called commencements. Graduating from any level of schooling is an accomplishment to be celebrated, but in terms of your life on this planet, it is just the beginning of a lifetime (at least one would hope so) of continuing to learn and making decisions grounded in sound principles informed by solid learning. Among the hardest tasks of anyone who hopes to be fully human rather than just a cog in the machine is deciding what principles will guide you and how closely you will adhere to them.

"In matters of style, swim with the current; in matters of principle, stand like a rock," Thomas Jefferson wrote to one of his nephews in one of the detailed letters of advice he lavished on younger relatives toward whom he felt some kind of tutelary obligation. But what is a principle, as compared to a fact, an opinion, a preference, a whim, a circumstance or a plan of action? And what do you do when your principles seem to clash?

First a demurrer. The idea that it is important to have coherent, consistent principles might not seem necessary - might not even seem efficacious - in the world graduates will be learning from. We all know of people who seem to survive and thrive with no particular principles, let alone consistent ones, beyond seizing opportunities, looking for the main chance, and shifting philosophical allegiances when the cultural winds shift.

The main reason to seek, hold and live by principles is for oneself, not for one's friends, neighbors or the world at large. The principled person can look back at a life and be able to say, "I wasn't perfect, and I might not have been successful as the world views success, but I had principles and I stuck to them. I was my own person." That beats having the pleasure of success tempered by the knowledge that you drifted or chose to behave less than honorably.

Kenneth Ellwein, executive director of Lutheran High School in Orange, of course, believes principles should be spiritually grounded, in Judeo-Christian teaching and scriptures. "Without such a grounding decision-making can be hit-or-miss," he told me. Whatever your religious orientation, if any, it can't hurt to operate as if a powerful, benevolent personage actively wants you to become better in every way throughout your life.

I believe there is such a person, so I try to be personally honest, which is not always easy for me; I'm often tempted to fudge - or let's be honest, lie - when I've done something stupid or embarrassing. I like Bob LeFevre's rule about personal conduct: "Harm no one; after that, do as you like." I believe personal coercion among adults is immoral, but I sometimes carry persuasion to the edge of coercion. I can't imagine starting a fight, but I stand ready to defend myself.

The Oxford English Dictionary defines "principle" as: "A fundamental truth or proposition on which many others depend; a primary truth comprehending, or forming the basis of, various subordinate truths; a general statement or tenet forming the (or a) ground of, or held to be essential to, a system of thought or belief; a fundamental assumption forming the basis of a chain of reasoning." A secondary definition is "A general law or rule adopted or professed as a guide to action."

I assume, for example, that people are created equal - not in the sense that they all have the same color hair or the same abilities or potential, but in the sense that none is entitled to special privileges, whether bestowed as a result of skin color, ethnic origin, sex or political influence. Equal in the eyes of God and (ideally) in the eyes of government. From that fundamental principle, it seems to me, one can derive the idea that (as Jefferson put it again) some are not born with saddles while others are born with boots and spurs, destined to rule the hoi polloi, and most of the other ideas that lead to the conclusion that a society in which people are free to make their own decisions about their own lives is preferable to any other.

But others might not agree with the entire chain of reasoning. And that general principle doesn't tell you whom you should support (if anyone) in a political race or what actions you should take to manifest your principles in the larger world. It doesn't tell you whether a particular function of government should be privatized tomorrow. That will require thought - sometimes deep, hard thought - and a clear-eyed view of the realm of the possible.

My favorite music is what we only half-accurately call "classical" and my favorite composer is Mozart. That's a preference, not a principle. It is probably a deep truth that music is important to human beings, but is any kind objectively best? Doubtful. In such areas one should enjoy what one likes and allow others to do likewise rather than trying to prove that one kind or another comports with your deepest principles.

That suggests a potential danger in living by principles: that they can devolve into a rigid ideology that pretends to explain everything and can cause you to deny or obfuscate inconvenient truths you may encounter. The Soviet communists believed so strongly that humankind could be molded into the perfect, socially responsible New Soviet Man that they denied the developing science of genetics and supported an alternate theory, Lysenkoism, that argued in the face of numerous countervailing facts that people are formed by society and have no inherent traits.

(The two views can be integrated into a view that both inherent characteristics and social circumstances influence human beings, but not if one is blinded by ideology.)

Ayn Rand loved the kind of light 19th-century overtures, dances and incidental music she called "lollipops." Fine. But she made a few desultory attempts to try to prove that such art was most conducive to an objectivist ethos and human freedom, while baroque music was degenerate and collectivist. Silly.

So there are pitfalls. You want to be careful about principles, searching diligently for ideals that are first principles rather than derivative ones. You don't want to base them on current scientific or sociological knowledge unless you are willing to change or abandon them if such knowledge is superceded. And you don't want to confuse your preferences or prejudices with genuine principles, or get so caught up in ideology that you come to view scientific or knowledge breakthroughs as potential threats to your belief system.

But think about a life without principles. You'll be blown about by circumstance, making compromises even when it's not necessary, worrying about how you will look to somebody else rather than how something you're thinking about doing comports with your inner compass. Your ethics are likely to be situational rather than grounded.

Living by principles requires constant thought about how to apply them and a willingness to challenge and rethink them. It will almost certainly require giving up some immediate benefits; it could mean choosing a less lucrative career path than might be available to those more willing to compromise.

But being true to yourself and your beliefs helps you to feel better about yourself. Constant thought - continuing to use and stretch your brainpower - wards off some of the ill effects of aging. So you'll live longer and be happier (though life without sorrow and tragedy is a delusion). Not bad.