Marsilio Ficino completed the third part of his De vita libri tres , titled De vita coelitus comparanda , in July of 1489; by the fall of that year he felt obliged to write an Apologia on behalf of his new book. Though it was destined to be the most popular of his original works, this analysis and defense of astrological magic and medicine caused Ficino worry from the moment of its composition. The Apology shows that he was particularly anxious about the religious orthodoxy of De vita III , among whose readers he expected to find many ignorant critics and some malignant: