The very last line of the memoir is when the Baroness looks back at the Ngong Hills from the railway station at Samburu. She sees where her farm lies, and that "the outline of the mountain was slowly smoothed and leveled out by the hand of distance" (5.5.29). There's a lot going on in this short, beautiful phrase, so let's get to work.
"The outline of the mountain" echoes another description of those hills, from way back in the very first chapter. There she says that sometimes it looks "as if in the sky a thin silver line was drawn all along the silhouette of the dark mountain" (1.1.6). That echo brings the book on home, closing it neatly, almost where it started.
And that almost is the kicker. The "hand of distance" is the difference between seeing the mountains from the farm and seeing them from the train station, far away from the home she'll never return to. That distance smoothens out all the details, making it hard to see. Maybe that's why Dinesen felt the need to write Out of Africa: so that she could remember the rough edges, instead of the "smoothed and leveled out" version.