On this day: 25 February AD 138
Hadrian the third of the so-called five good emperors adopted Antoninus Pius
continuing the policy established by Nerva of adopting the best man to become emperor.
Pius would become the fourth of the five good emperors and be responsive for the adoption of Marcus Aurelius.
Under Marcus the adoption principle was again replaced with hereditary succession which saw Rome burdened with Commodus.