How did the Renaissance affect slavery?

I feel that better answers could be gained if the wording
of the question was more along the lines of what would the Renaissance thinkers feel
about slavery.  There was still slavery despite the Renaissance, so the immediate answer
would be that there was little effect.  I do think that the humanism of the Renaissance
would speak quite loud to decry the dehumanization of slavery.  The power of the
Renaissance resided in its ability to praise education and the general notion of
individual knowledge.  On face value, both of these would go against the idea of
enslaving another individual.  It is difficult to envision the humanism that was so
stringently a part of the Renaissance would have tolerated or allowed the enslavement of
another.  If education was so important to the Renaissance movement, then the attempts
to enslave another and deny them education would be something that humanist thinkers who
played formative roles in the Renaissance would deride.  The glorification of Greek and
Roman ideals that was so prevalent in the Renaissance did not necessarily revere these
social orders because of slavery.  Hence, it would make sense that these particular
thinkers would not embrace it in their own setting.  Much of this is speculation because
the focus of art and artistic prowess in the Renaissance composed art for its own
intrinsic value and not for a larger statement about social conditions, of which the
stand on slavery would have been included.