Explain the line My last thought was at least not vain from The Last Ride Together

My last thought was at least not vain:
I and my mistress, side by side
Shall be together, breathe and ride,
So, one day more am I deified.
Who knows but the world may end tonight?” (Lines 18-22)

This is a passage extracted from Robert Browning‘s dramatic monologue The Last Ride Together. A lover is rejected by his lady. But she has agreed to ride with him for the last time. The lover feels elated at the prospect of one more ride with his lady. This is described here.

The lover’s last prayer for a last ride together has not been rejected. The lady will ride with him for one more occasion. The lover feels thrilled. He and his lady will sit side by side. They will ride together. They will enjoy the same air. The lover feels himself honoured. He fancies that the world may come to an end this very night. After all, nobody can say whether tomorrow will at all come. And if the world is destroyed tonight, the rejected lover will pass away as a fortunate man. He will be deemed as a successful lover who rides with his lady till the last day of his life.

The poet brings out here the psychology of the rejected lover who takes his rejection in a spirit of resignation and even feels a sense of immortality in his last ride together. He speaks out in his monologue his intense and ecstatic feeling after the lady’s favour to ride with him for one more time.

Also read: “The Last Ride Together” as a dramatic monologue