Editing Adoption in ancient Rome (section)

===The adoptive emperors===
[[File:HADRIANUS RIC II 3c-761923.jpg|thumb|[[Denarius]] issued under Hadrian; the reverse shows him joining hands with Trajan with the legend ''ADOPTIO'']]

The [[Nerva-Antonine dynasty]] was also united by a series of adoptions. [[Nerva]] adopted the popular military leader [[Trajan]]. Trajan in turn took [[Hadrian|Publius Aelius Hadrianus]] as his protégé and, although the legitimacy of the process is debatable, Hadrian claimed to have been adopted and took the name ''Caesar Traianus Hadrianus'' when he became emperor.

Hadrian adopted Lucius Ceionius Commodus, who changed his name to [[Lucius Aelius|Lucius Aelius Caesar]] but predeceased Hadrian. Hadrian then adopted Titus Aurelius Fulvus Boionius Arrius Antoninus, on condition that Antoninus in turn adopt both the natural son of the late Lucius Aelius and a promising young nephew of [[Faustina the Elder|his wife]]. They ruled as [[Antoninus Pius]], [[Lucius Verus]] and [[Marcus Aurelius]] respectively.

[[Niccolò Machiavelli]] described them as ''The Five Good Emperors'' and attributed their success to having been chosen for the role:
{{blockquote|From the study of this history we may also learn how a good government is to be established; for while all the emperors who succeeded to the throne by birth, except [[Titus]], were bad, all were good who succeeded by adoption, as in the case of the five from Nerva to Marcus. But as soon as the empire fell once more to the heirs by birth, its ruin recommenced.<ref name="Mac">Machiavelli, ''Discourses on Livy'', Book I, Chapter 10.</ref>}}
This run of adoptive emperors came to an end when Marcus Aurelius named his biological son, [[Commodus]], as his heir.

Adoption never became the official method of designating a successor, in part because Roman identity was based on citizenship with a visceral rejection of hereditary kingship. During the [[Principate]], so called from Augustus's styling of himself as ''princeps'' (first among equals, in the manner of the ''[[princeps senatus]]''), emperors consolidated their power by making use of the institutions of Republican Rome rather than overthrowing them outright. Augustus's early intentions seem to have been to apprentice and promote a successor on the basis of merit, but his longevity instead created an apparatus of centralized power from which his status as a private citizen could no longer be extricated. His fashioning of himself as "father of his country" enabled the transferral of his power over the Roman people in the same way that a ''paterfamilias'' of a family estate was bound to transfer his ''potestas'' whether or not the available successor was fully meritorious. A major transition in the means of imperial succession marks the periodization of Roman Imperial history into the  [[Dominate]], when [[Diocletian]] replaced adoption with the ''[[consortium imperii]]'', designation of an heir by appointing him partner in ''[[imperium]]''.