Rev Prof Henry Drummond FRSE LLD FGS was a Scottish evangelist, biologist, writer and lecturer.
Many of his writings were too nicely adapted to the needs of his own day to justify the expectation that they would long survive it, but few men exercised more religious influence in their own generation, especially on young men. His sermon "The Greatest Thing in the World" remains popular in Christian circles.
Wikipedia
Variant: You will find, as you look back upon your life, that the moments when you really lived are the moments when you have done things in the spirit of love.
