E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Vera Causa.
A cause in harmony with other causes already known. A fairy godmother may be assigned in story as the cause of certain marvellous effects,
but is not a vera causa. The revolution of the earth round the sun may be assigned as the cause of the four seasons, and is a vera causa.
