Once Plato determined that development of intellect and spirit is humankind's most noble task, he concluded that efforts must be made to eliminate any phenomena which was suspect for interfering with this task. He compulsively categorized such phenomena, and high on his list was sensual pleasure.
Plato, Aristotle, and Zeno had nothing against sensual experience per se, but since it involved the body, rather than the mind or soul, these philosophers concluded that any lower animal could experience the phenomenon, and they felt that it required resources and time which could be better spent focusing on mind and spirit.
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Thus, the ancient Greek philosophers adopted Zoroastor's Dualism and concluded that sensual pleasure was mutually exclusive with development of the mind and spirit. This permitted the philosophers to locate humankind in the overall life experience because it widened the perceived gap between other forms of life and human's seemingly special place in the scheme of things. And it was fully concordant with the accepted notion that humans resided at the center of the universe.
In fact, being at the center of the gods' universe was essential to Plato's view of humankind's divine intellectual and spiritual charter. After all, devotion to spiritual matters would be meaningless if no one were listening, and the best evidence that God was listening was the fact that he had placed man at the center of things.
In the 13th century A.D., Thomas Aquinas almost single handedly imported Dualism into mainstream Christianity. He attained international fame from authoring well-reasoned treatises which melded Plato's Dualism with current Christian philosophy, arguing that love of flesh was mutually exclusive with devotion to God. The Roman Christian church was eager to bring ever larger numbers into its confessionals, and Aquinas' treatises appeared to offer a nearly unlimited resource of sinners.
