Don't work for the food which perishes, but for the food which remains to eternal life, which the Son of Man will give to you. For God the Father has sealed him."
For this reason we must receive the gifts of the Spirit, that they may be earnests and pledges of eternal life. For, though the reprobate, after having tasted this food, frequently reject it, so that it is not permanent in them, yet believing souls feel that enduring power, when they are made partakers of the power of the Holy Spirit in his gifts, which is not of short duration, but, on the contrary, never fails. 