realism was the dominant philosophical school of Anselm's day, and stemmed from Platonism. It held, in contrast to Nominalism, that things such as "green" and "big" were known as universals, which had a real existence in an abstract realm, as described by Plato. Accordingly, if a concept could be formed in the human mind, then it had a real existence in the abstract realm of the universals, apart from his imagination. In essence, if God could be imagined, God existed. The ontological argument reflected the classical concept of "perfections". Size, intelligence, beauty, power, benevolence, and so forth: all the qualities are called perfections. What is more intelligent is more perfect as regards intelligence, what is more beautiful is more perfect as regards beauty, and so forth. Because existence was more perfect than non-existence and God was, by definition, perfect, God existed by definition. The Platonic concepts of realism, perfection and a god that defined as infinite thus became incorporated into Christian medieval philosophy. See also Constantinian shift Dehellenization of Christianity Hellenistic Judaism Jesus Christ the Logos Judaism and Christianity Neoplatonism and Christianity Neoplatonism and Gnosticism Pseudo-Dionysius the Areopagite Religio licita References Further reading Daniel W. Graham and James L. Siebach, "Philosophy and Early Christianity," 210-220. Cook, "How Deep the Platonism," 269-286 in Farms Review of Books, vol. 11, no. 2 (1999). Hebrew, Early Judaic, and Early Christian Thought External links Christian Platonists and Neoplatonists Christian philosophy Hellenistic philosophy and religion