Tobacco's but an Indian weed,
 Grows green at morn, cut down at eve,
 It shews our decay, we are but clay:
 Think of this when you smoke tobacco.

 The pipe that is so lily white,
 Wherein so many take delight,
 Is broke with a touch -- man's life is such:
 Think of this when you smoke tobacco.

 The pipe that is so foul within,
 Shows man's soul is stained with sin;
 It doth require the purging fire;
 Think of this when you smoke tobacco!

 The ashes that are left behind,
 Do serve to put us all in mind
 That unto dust return we must:
 Think of this when you smoke tobacco.

 The smoke, that does so high ascend,
 Shews us man's life must have an end,
 The vapour's gone -- man's life is done:
 Think of this when you smoke tobacco.

(17th Century England)

The song “Tobacco’s But an Indian Weed” goes back at least to the mid-17th century. It can be sung to an appropriately mournful, dirge-like melody.

This version is based on Thomas D’Urfey’s “Pills to Purge Melancholy”
(1699), sourced from: http://kitchenmusician.net/smoke/smokepage.html

— William Grey

Martin adds

What fascinates me about this song is how likely it is (at least in retrospect) that it would be caught up in the folk process. The combination of a simple, strong pattern (one rhyming couplet, one internally-rhyming line and a refrain), a subversive topic that has room for infinite variation, and the lack of any real ordering to the verses makes the temptation to tweak or add a verse or two almost irresistible.

Links

http://kitchenmusician.net/smoke/tobacco.html has a nice writeup on the history of the song