He was described by Heinrich Zimmer as "That noble scholar upon whose shoulders we are still standing." While serving as a curator to the Boston Museum of Fine Arts in the latter part of his life, he devoted his work to the explication of traditional metaphysics and symbolism. His writings of this period are filled with references to Plato, Plotinus, Clement, Philo, Augustine, Aquinas, Shankara, Eckhart, Rumi and other mystics. When asked how he defined himself foremost, Coomaraswamy said he was a "metaphysician", referring to the concept of perennial philosophy, or "sophia perennis".