Joseph was lying on the floor on his side, his head on his left arm, playing with two toy cars and singing one of my fiddle tunes. All I could make out was the meter of the tune. He had long since lost the melody, and his monotone, nasal la-la-la-ing altered only in dynamics - louder when the tune pitched up, quieter when it pitched down. He had the rhythm of it, a somewhat unique meter, but I only recognized it because I had just played it a half hour before. Normally, his singing is quite expressive for a three year old, but at that time it was not unlike the droning noise he makes when he is up past his bedtime.

And tired he was and had been for a couple of hours, the result of a late night and a full day, too tired to safely climb onto a couch, much less any climbing apparatus. Two hours earlier, he had mounted a vertical, three rung ladder at a playground - a feat he is more than capable of when well-rested - and then his feet slipped off and he plunged to the ground, his chin whistling past the metal ladder rails, narrowly avoiding an unexpected and unbudgeted trip to the emergency room by a centimeter. He lay on the ground without moving, waiting for the adrenaline haze to clear. By the time I had raced to him, he realized nothing was hurt at all and wrestled himself out of my arms and was running off again. Nevertheless, I revoked his pilot license and grounded him off the monkey bars for the rest of the afternoon.

Now the long day and previous late night were catching up with him.

"Joseph, let's go brush your teeth and get you in the bath."

Like a light switch, he was vertical, on his feet, jumping excitedly. "Yes! Yes! I want to bring my train. Can I have Thomas in the bath?"

"Yes, Joe, Thomas is a bath toy."

"Oh good! I want to play with her. Papa, will you brush my teeth in the tub?"

"No problem. Go pee on the toilet first."

"But I just peed AND pooped."

"That was an hour ago, and every time you get in this warm tub without using the toilet first, you always pee, at least a little bit. And I just don't think washing you with pee would be very smart."

"Good idea, Papa!"

He did his business on the toilet and got in the tub. I handed him the rubber-ducky Thomas the Train, a two-inch-long, flexible, plastic, hollow Thomas with a hole in its smokestack. He immediately dunked it underwater and started to drive it around. I gently held Joseph's head while I brushed his teeth and while Thomas idled, half-submerged, about his knees. When we were done, Joseph slid over on his belly and began to push Thomas slowly across the surface of the water.

"Look, Papa! She can drive underwater!"

"Very cool. Hey, Joe, I forgot. Why is this Thomas a girl?"

"Because my other Thomas is a boy."

"Oh, right. I remember now." The other Thomas being the wooden one in his track set, one of the few painted pieces that wasn't replaced in the recent lead paint recall. I watched him play, trying to fill Thomas and squirt the water out. "Can I try to fill him up for you? I mean, her?"

"Sure, Papa."

I submerged Thomas underwater and squeezed. A stream of noisy bubbles jetted from the smokestack and Joseph giggled.

"That's funny, Papa. Do it again!"

I did it again. Several times in fact, because in order to get all the air out of Thomas, I had to tip him ... I mean, her ... upside-down underwater and move the air trapped in his ... I mean, her ... tender over to the smoke stack. But as I squeezed the air out, some of the trapped air floated back into the tender. Several attempts and much giggling later, Thomas was now saturated, water-logged, and no longer floating. I picked him ... I mean, her ... up and flipped ... her upside down, and squeezed. A long satisfying jet of water came out, spraying the sides of the tub, the spigot, and Joseph himself.

"Stop, Papa!" he shrieked, laughing. "Let me do it!"

I handed him Thomas and he squirted water into the tub, very pleased and excited. Much experimentation with fluid dynamics, the mathematics of parabolas, and parental patience, but his high spirits were kept in check by his general fatigue. Finally he squirted Thomas upside-down, and a light of recognition appeared in his eyes.

"Papa! Look. Her smokestack is a penis and she's peeing out of her penis!"

*****

The other day, while having an afternoon snack, I overheard Hannah in the dining room ask Nola where babies come from.

I heard the drawn-out "Weeellll..." and in the pause that followed, I thought, "Good question. I wonder what the answer will be."

I had no thought of coming to Nola's rescue, and for the sake of my reputation, I must offer some justification, however weak. First of all, I was working in my office and under deadline. Secondly Hannah is a girl and Nola is a girl, and though the timing was roughly six years too early, it would have been Nola's job anyway. And finally, Nola is a physical therapist, trained in a medical school, with a graduate background in biology as well. Whereas I would have turned beet red and hemmed and hawed, and given any number of generally correct but slightly inaccurate answers, and would have avoided the main point at all costs, Nola, I was certain, would give an answer so medically complete, so biologically accurate, and so scientifically technical that Hannah would want to change the subject as quickly as possible. Clearly Nola was the man for the job.

And a fantastic job she did, explaining human anatomical development with the concise and accurate oration of a consulting family physician with whom you have already used up twenty of his allotted, HMO-dictated fifteen minutes.

But my prediction was wrong. Hannah listened with the infernal attention span of a Montessori alumna, and then followed up with the question she had been saving. "OK. But what I want to know is, how does the sperm get in there?"

I wish I could remember how Nola answered this question. The blood was pounding so hard in my ears, I'm not sure I heard it clearly anyway, but it was factually correct and appropriately dissimulating at the same time - a true masterpiece of parental tact and medical fact that somehow still preserved our daughter's innocent understanding of the world.

Five minutes later, Hannah was done eating and back to playing fairy games with her Polly Pockets. Nola came into my room, her forehead glistening, her face flush, her mouth dry and panting. I praised her performance, assured her that, with no preparation, she had done extraordinarily well, magnificent in fact, and I said (truthfully) that I had no criticism to offer whatsoever. Not that I would have been so stupid as to offer criticism at that particular juncture.

*****

"Say that again, Joseph?"

"Her smokestack is a penis and she's peeing out of her penis!"

"Uh, Joe..." OK, Matthew, whoa. Think about what you are going to say, before you say it. "Actually, Joe, boys have penises and girls have vaginas. So if your Thomas is a girl, she probably doesn't have a penis."

"Oh, OK." This seemed to puzzle him, but only for a moment. "OK, this is her anus. She's peeing out of her anus!"

This was getting complicated. Strategy was called for. Using that tone reserved by parents for when their children assert the ridiculous and you want to show that you are "in" with the joke (whether or not the child is "in" yet), I said "Joe, do you pee out of your anus?"

"Nooo!" he said, laughing at his own silliness.

"Nooo. You poop out of your anus, right?"

"Right, but ... but ... but, she's peeing AND pooping out of her anus."

"Um ... ok, but..."

"No, no, no, wait. The smokestack ... is her scrotum..."

"Uh..."

"and she's peeing and pooping into her scrotum!"

He looked so sure of himself, as if I couldn't possibly contradict him, and I couldn't. For a moment I thought of Nola, next door, reading a bedtime book to Hannah, but even if she were available, I could not possibly have asked her for assistance and still looked at my reflection in the morning.

"Uh, ok, Joe. Just ... uh ... just keep it inside the tub, ok?"

"OK, Papa."