These famous words by John Donne were not originally written as a poem - the passage is taken fromn the 1624 Meditation 17, from Devotions Upon Emergent Occasions and is prose. The differences are reflected below.

"For Whom the Bell Tolls"

No is an island,
Entire of itself.
Each is a piece of the continent,
A part of the main.
If a clod be washed away by the sea,
Europe is the less.
As well as if a promontory were.
As well as if a manner of thine own
Or of thine friend's were.
Each man's death diminishes me,
For I am involved in mankind.
Therefore, send not to know
For whom the bell tolls,
It tolls for thee.

"Devotions Upon Emergent Occasions"
Meditation 17

"No man is an island, entire of itself; everyman is a piece of the continent, a part of the main. If a clod be washed away by the sea, Eurpoe is the less, as well as if a promontory were, as well as if a manor of thy friend's or of thine own were. Any man's death diminishes me, because I am involved in mankind; and therefore never send to know for whom the bell tolls; it tolls for thee..."