Bernard Lewis writes: "In one of the sad paradoxes of human history, it was the humanitarian reforms brought by Islam that resulted in a vast development of the slave trade inside, and still more outside, the Islamic empire." He notes that the Islamic injunctions against the enslavement of Muslims led to massive importation of slaves from the outside. According to Patrick Manning, Islam by recognizing and codifying the slavery seems to have done more to protect and expand slavery than the reverse.