Auguries of Innocence

To see a world in a grain of sand,
And a heaven in a wild flower,
Hold infinity in the palm of your hand,
And eternity in an hour.

This is the famous starting line of the extremely long poem, Auguries of Innocence, by William Blake.

Months ago, I was shown this poem. The previous time when I came across it, I didn't really catch the meaning and beauty of the words. But this second time I have, and it is one of the best lines I've heard in my life.