In the West, Peter Lombard's 12th-century "Sentences", wherein he thematically collected a great series of quotations of the Church Fathers, became the basis of a medieval scholastic tradition of thematic commentary and explanation. Thomas Aquinas's "Summa Theologiae" best exemplifies this scholastic tradition. The Lutheran scholastic tradition of a thematic, ordered exposition of Christian theology emerged in the 16th century with Philipp Melanchthon's "Loci Communes", and was countered by a Calvinist scholasticism, which is exemplified by John Calvin's "Institutes of the Christian Religion".