Aristides was an Athenian Christian philosopher who, around AD 124 or AD 140 (sources vary), addressed his Apology to the Emperor Hadrian (or possibly Antoninus Pius — the inscription survives in two forms). The full Greek text of the Apology was lost for centuries and known only from Eusebius's brief reference, until in 1889 the Mechitarist scholar Karapet Ter-Mkrttschian discovered a complete Armenian translation at the monastery of Edjmiatzin, and in 1891 the British scholar J. Rendel Harris discovered a complete Syriac translation at Mount Sinai. The Greek original was then partially reconstructed from the medieval Greek hagiographic romance The Story of Barlaam and Joasaph (which had embedded long sections of Aristides's apology into its narrative).
The Apology is the earliest surviving complete Christian apologetic treatise. Its philosophical structure — a systematic typological survey of human religions (barbarian, Greek, Egyptian, Jewish, Christian) showing the relative inadequacy of each non-Christian religion and the unique adequacy of Christianity — became the foundational model of Catholic philosophical apologetics, deeply influential on Justin Martyr (a generation later) and through Justin on the entire patristic apologetic tradition.
Aristides's description of Christian moral life (chapter 15 of the Apology) is one of the most beautiful early extant descriptions of the Christian community: 'They love one another. They never fail to help widows. They save orphans from those who would hurt them. He who has gives to him who has not, without boasting. And when they see a stranger they bring him under their own roof and rejoice as if it were a brother…'