Another work, based on the formula of Concord, was entitled Loci communes theologici.
Of a controversial character are the Confessio Catholica, (1633-1637), an extensive work which seeks to prove the evangelical and catholic character of the doctrine of the Augsburg Confession from the writings of approved Roman Catholic authors; and the Loci communes theologici (1610-1622), his principal contribution.
As Duke Albert sided with Osiander, Chemnitz resigned the librarianship. Returning (1553) to Wittenberg, he lectured on Melanchthon's Loci Communes, his lectures forming the basis of his own Loci Theologici (published posthumously, 1591), which constitute probably the best exposition of Lutheran theology as formulated and modified by Melanchthon.
At Bologna he read Melanchthon's Loci communes theologiae and was so impressed by it that in 1549 he went to Wittenberg to see the author, and shortly afterwards became a Protestant.