Alone, an old man sits with his memories, and two of them rise above the rest: his first love and his last. That is all the poem tells us, and the brevity is the point. It says very little, so we are left to fill in the story ourselves.
The word "Alone," sits by itself on the first line, followed by a comma, as if the speaker has paused. It sets a quiet, solitary scene. The poem doesn't say whether the old man is lonely or simply at peace, and it doesn't say whether the two loves are the same person or different people. Perhaps that is the question it wants us to wonder about.
The mood is gentle and wistful, with a thread of sadness running through it. The speaker seems to look on the old man with tenderness. The short lines feel like his thoughts: few, slow, and carrying a great deal of weight. Sometimes a whole life can be held in a single sentence.