The first was that he was a Martian little boy. You could be very sure of that, for Earth little boys have earlobes while Martian little boys do not—and he most certainly didn't.
The second was the tune he whistled—a somehow familiar tune, but one which I should have thought not very appealing to a little boy.
"Hi, there," I said when he came near enough. "What's that you're whistling?"
He stopped whistling and he stopped walking, both at the same time, as though he had pulled a switch or turned a tap that shut them off. Then he lifted his little head and stared up into my eyes.
"'The Calm'," he said in a sober, little-boy voice.
"The what?" I asked.
"From the William Tell Overture," he explained, still looking up at me. He said it deadpan, and his wide brown eyes never once batted.
"Oh," I said. "And where did you learn that?"
"My mother taught me."
I blinked at him. He didn't blink back. His round little face still held no expression, but if it had, I knew it would have matched the title of the tune he whistled.