“This [insistence that all people had dignity, and the most wretched especially] was the conviction that in 369, on the outskirts of a Caesarea ravaged by famine, prompted Basil to embark on a radical new building project. Other Christian leaders before him had built ptocheia, or ‘poor houses’ – but not on such an ambitious scale. The Basileias, as it came to be known, was described by one awestruck admirer as a veritable city, and incorporated, as well as shelter for the poor, what was in effect the first hospital. Basil, who had studied medicine while in Athens, did not himself scorn to attend the sick. Even lepers, whose deformities and suppurations rendered them objects of particular revulsion, might be welcomed by the Bishop with a kiss, and given both refuge and care. The more broken men and women were, the readier was Basil to glimpse Christ in them. The spectacle in a slave market of a boy’s sold by his starving parents, the one child sacrificed that his siblings might have some few scraps of food, provoked the bishop to a particularly scorching excoriation of the rich.... Basil's brother went even further. Gregory was moved by the existence of slavery not just to condemn the extremes of wealth and poverty, but to define the institution itself as an unpardonable offence against God. Human nature, so he preached, had been constituted by its Creator as something free. As such, it was literally priceless. ‘Not all the universe would constitute an adequate payment for the soul of a mortal.’… Gregory's abolitionism met with little support. The existence of slavery as damnable but necessary continued to be taken for granted by most Christians – Basil included..”
Tom Holland Dominion: How the Christian Revolution Remade the World [but you have to start somewhere, and abolitionism more or less started here].