 Origen (c. 185–c. 253) was a Christian exegete and theologian, who made copious use of the allegorical method in his commentaries, and (though later considered a heretic) laid the foundations of philosophical theology for the church. He was taught by a certain Ammonius, whom the majority of scholars identify as Ammonius Saccas, the teacher of Plotinus; many believe, however, that the external evidence will not allow us to identify him with the Origen whom Plotinus knew as a colleague. He was certainly well-instructed in philosophy and made use of it as an ancillary to the exposition and harmonization of scripture. This was the task that he undertook in most of his extant writings, and the more systematic theology is founded on the ecclesiastical doctrines of the Trinity, the incarnation, salvation after death and the inerrancy of scripture.