Alice Boner (1889–1981) was a Swiss-trained sculptor and artist who lived in the ancient Indian city of Varanasi from 1936 until 1978. She made significant contributions to the culture of India through her realization and explication of the geometrical principles underlying India's ancient temple cave art, principles that are unlike anything with which we are familiar in western art. The question we raise here is to what extent these principles entered into her own art, and in particular into her great triptych based on the Indian trinity of gods, Shiva, Vishnu, and Brahma. We know from her diaries (Boner 1993) that the creation of this triptych was extraordinarily important to her and occupied a number of years of her life. Although it seems to have passed by unnoticed, we argue here that an analysis of the triptych makes it abundantly clear that indeed the underlying structure of these three paintings is based precisely on these geometrical ideas, and so reveals hidden layers of meaning within them. In this paper, based on her diary, her book on Hindu sculptures, and a detailed look at the triptych, we discuss the remarkable geometric principles which lie at the root of Indian temple cave art and the way in which Alice Boner implemented them in her great paintings.