Mantre Thaddhevathayam cha thatha mantra Pradhe gurau,
Thrishu bhakti sadha karya saahi prathama sadhanam

The above sloka says that while reciting a mantra, a person should have complete devotion to the mantra which is of primary importance, next to the God or Goddess to which this mantra is oriented and then to the Guru (Teacher) who has imparted the mantra. The mantra is supposed to yield results only when all the above are followed by the reciter.

Mantraadheenam Jagatsarv daivadheenam thu manthritham
Thanmanthram brahmanadheenam brahmano mama dhevatha

It says that the whole world is under the control of mantras. These mantras are under the control of God, which in turn are in the control of brahmins.