St John of Avila, proclaimed a doctor of the Church in October 2012, offers illuminating insights on the Holy Spirit in the collection of homilies first published by Scepter in 1959. Presented as sermons given around the feasts of Ascension and Pentecost, the saint speaks directly and to the point, yet is thoughtful and affectionate in his style. He proceeds in the form of a dialogue to present the Great Unknown. The sermons begin with a short introduction and then come to a particular point supported by Scripture texts, quotations from the Fathers, well-chosen illustrations, and his own original insights. Many believers may find these feasts somewhat puzzling and obscure. St. John shows how they are among the greatest feasts in the Christian calendar and deserve to be better understood.