[jaldhar]

The Greek authors naturally were not completely versed in the ins and outs of Indian traditions so they confused different social phenomena. There was no “Sage caste” but there were different orders of monks following different philosophies. They are loosely grouped together as Shramanas and they generally believed that this world was illusionary and full of suffering and the task of religion is to find a way out. Some of the more pessimistic ones thought that the only truly nonviolent way to do it is by suicide. This is an official dogma of Jainism to this day (though Darwin has moderated actual practice considerably.)

Sati is a different social custom from a much later time period.