"Are there religions and communities in the East which accept the Teaching about Maitreya? The Bodhisattva Maitreya was promised to the world as the coming Buddha by Gautama himself. This is the reason why the Hinayana also accepts this one Bodhisattva. Maitreya corresponds to the Kalki Avatar in Hinduism (the "White Horse Avatar"—see the Revelation of St. John), and to the Messiahs of all nations. All the Messiahs are inevitably Avatars of Vishnu; therefore, they belong to One Ego. (19 March 1936)"
January 1, 1970
https://en.wikiquote.org/wiki/Helena_Roerich