The poem sets two scenes side by side. First we see a crowded hall, full of people who seem ready to come alive once night falls. Then the speaker turns inward, and the contrast is sharp: while others gather and wait for the evening's energy, he sits drinking bourbon through the summer, his own life "still as winter light."
The middle line, "mortality is a great blessing to us," reads like a calm, slightly wry remark. It suggests that knowing our time is limited is what gives life its weight, and maybe what makes those people so eager to live at night. The speaker seems to accept this, but without much excitement.
The mood is quiet, reflective, and a little lonely. Summer usually means warmth and activity, yet the speaker feels cold and motionless, like thin winter sunlight. The title's pun on "bourbon" and "Bourbonic" adds a touch of dry humor, as if he is half-joking about his own drinking and stillness.