Mary wasn’t sure what to make of some of them, where the images seemed to her to be random. But a glance at Gretchen and the way she was studying them carefully told her that there must be some special observation at work, some organization of image that she herself had not yet understood. It was strange to look at Theodore, too. He was still the same young fellow with the wide-set eyes that she had always known, but the self-absorbed seriousness that had seemed so funny and endearing in his childhood had turned into something else now that he was a young man. There was a concentration and intensity in his face that reminded her of the look on Hans’s face when he had played the piano for her. And seeing the brother and sister together, sharing this art that she did not understand, she couldn’t help wishing that she could share these things with them too.

One picture in particular struck her. It was taken on the West Side, where the line of railroad tracks ran up alongside the River Hudson. Above, there were heavy clouds, whose gleaming edges seemed to echo the dull gleam of the metal tracks below. The river was not gleaming, though, but lay like a huge, dark snake beside the tracks. And upon the tracks, some close by, others already far in the distance, walked the sad, scattered figures of Negroes, leaving town.

It was a common enough sight, she had no doubt. The underground railroad, as everyone called it, had always brought escaped slaves up to New York. But now, with the Civil War raging, that trickle had turned into a flood. And when this tide of Negroes reached New York, they mostly found neither jobs nor welcome, so that, on any day, you might see them setting off up another kind of railroad, hoping maybe to catch a ride on a passing train, or at least walk along the iron road that led to the far north, in the hope of a warmer reception somewhere there.

With its strange, eerie light, the hard gleam of the tracks and the blackness of the river, the photograph captured perfectly the desolate poetry of the scene.

“You like it?” asked Theodore.

“Oh yes,” she answered. “It’s so sad. But …”

“Harsh?”

“I didn’t realize that a rail track like that”—she hardly knew how to say it—“could also be so beautiful.”

“Aha.” Theodore looked at his sister with a pleased expression. “Mary has an eye.”

They had to leave soon after that. But as the carriage took them southward toward the ferry, Mary turned to her friend and said: “I wish I understood photographs the way you do, Gretchen.”

Gretchen smiled. “Theodore taught me a little, that’s all. I can show you some things, if you want.”