The word was borrowed, as he himself says, from the usage of the classic rhetoricians, in whose works topoi or loci, denote the places or sources from which proofs are deduced.
Various systematized indexes of these loci were made from the days of Aristotle, and mere formal categories, such as "person," "nature," or "fortune," were also reckoned under this head.
Melanchthon accordingly advised them to prepare lists of all possible loci communes, and to enter under the proper rubrics (capita) any examples gathered in the course of their reading.
Among theological loci communes he lists "faith," "destruction of the body," "Church," "word of God," "patience," "sin," "law," "grace," "love," and "ceremony."
In view of the long and powerful influence of this book, the result of his failure to give a methodical proof of his series of loci was that Lutheran dogmatics was slow in reaching inherent unity.
Among the Reformed the phrase loci communes was accepted by Wolfgang Musculus (Basel, 1560), Peter Martyr (London, 1576), Johannes Maccovius (Franeker, 1639), and Daniel Chamier (Geneva, 1653).