Attributes such as the courage, valour, knowledge, and the bodily health of the Brahmin sages are stated to have been milked from the earth, Bhudevi, and the virtues and the truths that characterise animals may be attributed to her as well.
There is a very well-recounted legend in regards to how Bhumi ended up contributing such attributes to the world, and it is with the emperor of the world, Prithu.
One day, Bhudevi stopped providing vegetation for humans.
Prithu, the emperor of the world, got angry on hearing this and taking his bow Ajagava and several arrows went in search of the goddess of earth.
The goddess got frightened and fled taking the form of a cow. She went to all lokas but Prithu followed her with his bow and arrows everywhere.
At last desiring to escape from the arrows of such a valiant king Bhumidevi went to him and said "Oh king, I shall give you back all I have destroyed in the form of milk. Therefore, virtuous as you are, if you are really interested in the welfare of the people I shall allow you to milk me and take back everything you want. Do bring a calf."
This was how the virtuous age of sages came into being.