How do poets utilize literary devices and conventions to develop themes in their poetry?

Question

Good explanation here: "Language is a means of communication by symbolic sounds and graphics. The meaning of these symbols is affected by the use of literary devices which further enhance, illuminate, and embellish them. Effective speakers and writers have always made good use of literary devices and accommodative language."
from http://www.freedomsring.org/ftc/chap8.html

And here: http://mrbraiman.home.att.net/lit.htm

http://en.wikipedia.org/wiki/Literary_device

http://www.dean.tec.ma.us/MCAS/mcasst.htm