Judges 7:6

Dogs are commendable, not abominable. They observe fidelity toward their master, and before his house they bark against enemies. He has not simply said "of dogs" but "of your dog." Nor are their teeth praised, but their tongue is: for it was not indeed to no purpose, not without a great mystery, that Gideon was bidden to lead those alone who should lap the water of the river like dogs. Of such sort not more than three hundred among so great a multitude were found. In this number is the sign of the cross because of the letter T [tau], which signifies three hundred in the Greek numeral characters.

Dogs should not always be taken in an evil sense; otherwise the prophet would not blame "dogs not able to bark and loving to dream." Doubtless they would be praiseworthy dogs if they both knew how to bark and loved to watch. And certainly those three hundred men—a most sacred number according to the letter of the cross10—would not have been chosen to win the victory because they lapped water as dogs do, unless some great mystery were signified. Good dogs watch and bark to protect their house and their master, their flock and their shepherd. Finally, even here in the praises offered by the church, when a selection is made from this prophecy, it is the tongue of dogs that is mentioned, not their teeth.

Limiting one's intake of water helps a great deal to obtain temperance. This was well understood by the three hundred Israelites accompanying Gideon just when they were preparing to attack Midian.

This was marked in the case of Gedeon where those who were tested by the water, that is, those who lapped it like dogs, fought the battle and won, while those who bent their knee to drink were turned away. And those who had won …

And they are brought to the river, to drink the waters; and whoever drank the waters with bended knees, were removed from the struggle of war. For by the waters is designated the doctrine of wisdom, but by the unbended knee righteous conduct. They therefore who are reported to have bent their knees, while drinking the water, retired from the strife of battles, having been forbidden; because Christ proceeds to battle against the enemies of the faith, with those who when they drink the streams of doctrine, distort not the uprightness of their actions.