From the Sun God the Incarnation of Rama, from the Moon that of Krishna, from Mars that of Narasimha, from Mercury that of Buddha, from Jupiter that of Vamana, from Venus that of Parasurama, from Saturn that of Koorma (Tortoise), from Rahu that of Varaha [Boar] and from Ketu that of [Matsya] (fish) occurred. All other incarnations that these are through the Grahas. The beings with more Paramatmamsa [i.e. Rama, Krishna, Narasimha and Varaha] are called divine beings’.
— Brihat Parasara Hora Sastra, Translated by R. Santhanam (1984), Chapter 2, Verses 5-7