“Any work that aspires, however humbly, to the condition of art should carry its justification in every line.” ~ Joseph Conrad
I would add: “in every word.”
I try to be conscious of every word I use, not just for its color, smell, feel and possible deeper metaphorical associations, but for its rhythm in the sentence. Never a great student of poetry, I am a great lover of music, and I believe good prose must have movement, tone, meter — all of which envelop the reader in additional layers of meaning, giving her/him extra pleasure in the reading. Besides, it’s more fun to write this way!