‘Venerable Nāgasena, that one quality of the rat you say he ought to take, which is it?’

‘Just, O king, as the rat, wandering about backwards and forwards, is always smelling after food ; just so, O king, should the strenuous Bhikshu, earnest in effort, be ever in his wanderings to and fro, bent upon thought. This is the quality of the rat he ought to have. For it was said, O king, by Upasena Vaṅganta-putta, the Elder:

“Ever alert and calm, the man of insight,
Esteeming wisdom as the best of all things,
Keeps himself independent of all wants and cares.”’