I know because I'm a Nats season-ticket holder. My Nats moment happened a few Sundays ago. My son David and I were returning home on the Metro, Washington's subway system. His head was resting on my shoulder and I must have had an odd look on my face because David asked me, "are you okay, Dad?" As a matter of fact, I was more than okay: I was content. Not only because the game I've loved all my life was now playing at a ballpark near me but because of who was with me at the ballpark. Moments like that one reminded me that however hard it was being David's dad, it was worth it and then some. In fact, I don't think I would change a thing.

Just as marriage holds out the possibility that one plus one can equal more than two, fatherhood can transform the lives of both fathers and their kids in ways they can't foresee.

This bond is what the creators of Father's Day (no, it wasn't Hallmark) had in mind. We think of Father's Day as a day to honor and remember our fathers, but the original intent had more to do with turning men into good fathers. When Calvin Coolidge proclaimed the first national Father's Day in 1924, he said the purpose of the holiday was to "establish more intimate relations between fathers and their children and to impress upon fathers the full measure of obligations."

Silent Cal's proclamation anticipated (by seventy years!) the 1990s arguments over the effects of fatherlessness -- whether through divorce or out-of-wedlock births -- on children. At this point, it requires a kind of perversity to deny that fathers who do not meet "the full measure of obligations," both financial and emotional, towards their children are putting their kids' well- being at risk.

Still, something is missing here: a sense that being a good father is, well, good for the father. The arguments, with their nearly- exclusive emphasis on the kids' well-being, remind me of the explanation offered by evolutionary psychologists and other Darwinians for why the males of some species -- such as humans -- don't abandon the mother after impregnating her. By "cooperating" with the female and caring for his children, they hold, the male assures that his progeny reach adulthood and, thus, spread his genes to another generation.

I doubt that even the most convinced Darwinian thinks that way about his own children. I know that neither my friends nor I think the only ones who benefit in their relationship with their children are the kids. We've learned that just as marriage holds out the possibility that one plus one can equal more than two, fatherhood can transform the lives of both fathers and their kids in ways they can't foresee. It's certainly true for me. Being David's father has made me a better man and a better Christian than I could have been otherwise. The lessons I've learned from my son are lessons I doubt I would have learned from anyone else.

For instance, like many people I've struggled with the idea of calling. As it was originally articulated by Martin Luther and other magisterial reformers, calling affirmed the dignity and worth of the work done by ordinary people. Luther went so far as to say that "household chores are more to be valued than all the works of monks and nuns." Yet over time, calling ceased being a way of affirming the value of our work, no matter what it might be, and, instead became what it had been intended to replace: a way of elevating some vocations and professions over others. Only this time, instead of a simple division between the clergy and the laity, the value of work became a function of its prestige, remuneration or its impact on those around us. Work ceased being a means to an end -- providing for your family -- and became an end in itself.

Christians aren't immune to this thinking. While prestige and pay don't figure as prominently in their vocational calculus, that only leaves more room for impact. Countless Christian are urged to -- in a phrase that Luther would have responded to with a pork loin upside the head -- "do something great for God." The "something" historically meant a full-time ministry of sorts. More recently, "something" has expanded to include politics, public policy and other culture-shaping endeavors. In all of these, the value of our work lies in its impact on people you haven't met and probably never will.

I wasn't immune to this kind of thinking. Not by a long shot. But being a father has helped me realize that our calling begins with the people you see everyday. In my case, that means David. God has entrusted me with the care and nurture of someone He loves very much. On this side of eternity, I am standing in for the "Father, from whom every family in heaven and on earth is named" (Ephesians 3:15). Everything I do and every decision I make starts from this knowledge.

This doesn't give my work less meaning; it gives it more. Instead of expecting work to provide me with significance and satisfaction that it probably can't, being a father makes work part of a satisfying and definitely significant whole. Work, instead of being a quest for affirmation, becomes an act of love -- something you do for others.

I like to think I would have learned these lessons even if David weren't autistic. I'll never know. What do I know is that, as I said earlier, I wouldn't change a thing, at least not for my sake. I'm not saying that being a father is easy. Far from it. I'm saying that all the work is definitely worth it. My strivings, which managed to leave me both exhausted and restless, are being replaced by the satisfaction that comes from knowing you're doing what you're supposed to be doing. It's the kind of satisfaction that can turn the Metro into a slice of Heaven.