The Ram is called in Egyptian ba on account of the digs which he makes with his head, and a force which has occasioned the name of 'ram' to be given to powerful engines. The Heron is also called ba because with its bill it cleaves the fishes which it attacks. And the word which we translate Soul or Spirit is called ba, because it is conceived as something which 'pierces, penetrates and divides.'
Source: tatoeba (9503044)