During the Civil War, Ulysses S. Grant sent a lock of hair to his wife, Julia, nestled inside a sweet love letter to her. And years before, while serving in the Mexican War, he sent her a note with this postscript: "Before I seal this, I will pick a wildflower off the bank of the Rio Grande to send to you."

And even today, when you look at that faded piece of paper, you can see the 170-year-old imprint of the little flower.

The Library of Congress has volumes and volumes of these original love letters, which paint a softer portrait than history tends to remember of the determined general who led the Union to victory in the Civil War—and who would then go on to be 18th president of the United States.

This week's episode of the Presidential podcast explores Grant's writing with Michelle Krowl, a expert on the Civil War and Reconstruction who oversees those presidential manuscripts at the Library of Congress. It also features Washington Post journalists Carlos Lozada and David Maraniss discussing Grant's greatest written work—his personal memoirs, which he wrote on his deathbed and which were then published by Mark Twain.

You can listen to the new episode here:

In previous episodes of the Presidential podcast, we've explored topics like Abraham Lincoln's language and the violent life of Andrew Jackson. The podcast is hosted by Lillian Cunningham, editor of The Washington Post's On Leadership section.

As listeners tune in each week, the podcast reveals the ways in which our collective sense of what’s ’presidential’ has evolved over the years and how each president—esteemed, loathed or nearly forgotten—has something to tell us about what it takes to hold the nation’s highest office.

A new episode comes out every Sunday. Here's how to follow along: