"A thirsty man is . . . not depressed because he cannot exhaust the spring"

Source

"A thirsty man is happy when he is drinking, and he is not depressed because he cannot exhaust the spring. . . .
     "Be thankful then for what you have received, and do not be saddened at all that such an abundance still remains. What you have received and attained is your present share, while what is left will be your heritage. For what you could not take at one time because of your weakness, you will be able to grasp at another if you only persevere. So do not foolishly try to drain in one draught what cannot be consumed all at once, and do not cease out of faintheartedness from what you will be able to absorb as time goes on."

     St. Ephrem the Syrian, Commentary on the Diatessaron 1.18-19, as trans. Office of readings for the Sixth Sunday in Ordinary Time, Liturgy of the hours.  SC 121 (1966), 52-53.  Cf. Saint Ephrem's Commentary on Tatian's Diatessaron:  an English translation of Chester Beatty Syriac MS 709, trans. Carmel McCarthy,  Journal of Semitic studies. Supplement 2 (Oxford University Press on behalf of the University of Manchester, 1993).