Complex sentence: Rivera first became passionate about ceramics in the early 1970s when he studied in Cuernavaca, Mexico with Paulo Freire and Ivan Illich, who taught that human beings had lost their connection with the earth.
Split into simpler sentences: Rivera first became passionate about ceramics in the early 1970s when he studied with Paulo Freire and Ivan Illich in Cuernavaca, Mexico. From these teachers, he learned that human beings had lost their connection with the earth.