amantramakṣaraṃ nāsti nāsti mūlamanauṣadham |
ayogyaḥ puruṣo nāsti yojakastatra durlabhaḥ ||
There is no letter which is not a mantra(which cant be used in mantra). There is no root, which can’t form some medicine. There is no person who is absolutely useless. But persons who can identify their utility and put them in proper usage are rare.