Faith cannot be legislated even by scriptural injunctions. It can only arise by hearing, seeing, and associating with those who have faith in pure devotional service. In the market place of the holy name, the most valuable commodity is faith. Just like a mundane investor who wishes to invest his wealth looks for a solid investment which will hopefully give him a good return, similarly one who has some faith in pure devotional service and the holy name, but also wants to increase it, has to be willing to invest their faith in that person who invokes faith in pure devotional service and the pure holy name. The more faith invested, if it is a genuine solid investment, the more we will get in return.
(Letter to disciples and friends)