Nearly a century ago, Thaddeus Marshall left a major mark on the world of American poetry, but he didn’t know it. The rest of the world wouldn't know it, either—until now.

Marshall's red wheelbarrow was likely the subject of poet William Carlos Williams’ most famous work, 16 simple words that have been read and analyzed over and over in classrooms for decades:

so much depends
upon

a red wheel
barrow

glazed with rain
water

beside the white
chickens.

"The Red Wheelbarrow" was published in 1923; Marshall died seven years later. His unmarked grave at New Jersey’s East Ridgelawn Cemetery will get some long-overdue adornment this Saturday, when the families of both the poet and the owner of its inspiration will gather to eulogize Marshall and add a headstone to his resting place.

William Logan, a professor at the University of Florida, tracked down Marshall’s identity when he was in the process of writing a 10,000-word essay on the poem. It was perhaps an unobvious quest for a 92-year-old poem with no actual people in it.

“When we read this poem in an anthology, we tend not to think of the chickens as real chickens, but as platonic chickens, some ideal thing,” Logan told The New York Times.

In his search, Logan found some clues from Williams himself. In a 1933 anthology called Dreaming and Storytelling, he said he had seen the wheelbarrow “outside the window of an old negro’s house on a backstreet” in Rutherford, N.J. Williams, who was also a physician, often made house visits to patients in that predominantly African-American neighborhood. Later in an essay in Holiday magazine in 1954, Williams noted that the man’s last name was Marshall, and he had a son named Milton.

“I suppose my affection for the old man somehow got into the writing,” he wrote.

Logan then tracked down the 1920 census and found only one Marshall who fit the profile: a 69-year-old man with a son named Milton who lived just blocks away from Williams’ house. Rutherford borough historian Rod Leith was even able to find a 1917 fire insurance map which revealed a chicken coop at the back of the property.

Marshall was a street vendor, though it’s unclear whether he was using the red wheelbarrow for those purposes when Williams found his inspiration. Regardless, the sight made an impression on Williams and, through him, the world.

“The sight impressed me somehow as about the most important, the most integral that it had ever been my pleasure to gaze upon,” he wrote in Dreaming and Storytelling.