Who am I? Who are you? And who the heck -- we would like to know -- are they?

It's such a lovely day that I thought I would shake it up a bit by pondering one of the great head-scratchers of all time; that is, what really is our human nature?

Far more agile minds than mine have tackled this question up and down and all around since humans started walking upright, lighting fires and plastering their hands on the inside of caves.

From before Plato and on to Aristotle and Lao-Tse and Rousseau and Locke and Marx and Darwin and Freud and Arendt and E.O. Wilson -- and so many in-between -- the great thinkers have wracked their brains over who, what and why we human beings are.

The conclusion from the big wigs, I'm sorry to report, is inconclusive. No one, it turns out, really knows.

The human being's first duty...is to think about himself until he has exhausted the subject, then he is in a condition to take up minor interests and think of other people. -- Mark Twain

My own limited view is that we -- all six point eight billion of us -- are but minor variations on a single theme. No exceptions. Like separate little ditties, we are each composed with a set number of notes -- all that differentiates us is the configuration.

So what are those notes? They're what determine our skin, hair, eye color and other physical features, of course, plus some personality characteristics and a predisposition to certain abilities, diseases and disorders. Scientifically minded people call them genes.

Those notes also make us animals; they make us want to eat, sleep, reproduce and fight to survive. And they make us human -- they spur us to love and be loved, to laugh and to cry, to think too much and to try and drive faster than the bozo in the next lane.

We each get a unique collection of good notes and bad notes. Of high notes and low notes. Of middle notes and post-it notes.

It is our job to make the best of them.

But if we don't like our personal set of notes, can they be altered? And even more importantly, can the theme itself be changed?

Many of us, especially Americans, are blessed and cursed with the idea that if we try really, really hard, we can transform ourselves into something completely new. We are constantly spurred on to remake ourselves, especially if we feel we were created in the wrong key.

Everybody wants to be Cary Grant. Even I want to be Cary Grant. -- Cary Grant

My cats can't become dogs (not that they want to) and a sheep cannot possibly -- no matter how much it might gaze longingly into the next meadow -- turn into a cow. A maple cannot transform itself into an oak and a cricket can't morph into an ant.

But what is that theme of which we humans are just a minor variation? Ah, therein lies the unanswerable question. Are humans mere shreds of matter that just happened to evolve into our current form? Or are we the children of Adam molded by a God who loves us? Or something else altogether?

I was just admonishing my cat this morning to make more of an effort to become an athlete. "You're an American cat, Booboo," I said. "You need to exercise more. It'll help lower your cholesterol and prevent osteoporosis. We can go out running together. Come on. Do it for me."

She looked at me with that icy gaze usually reserved for staring down canines, knowing full well -- and seemingly comfortable with the knowledge -- that she is but a minor variation on the ineffable theme of cat.

And as for her humans:

Whatever you may be sure of, be sure of this: that you are dreadfully like other people. -- James Russell Lowell

The music, as always, plays on.