Bede : Their horses were six hundred and thirty-six, etc. A mule is born from a donkey and a mare, a she-mule from a horse and a she-donkey. Hence, among the people who ascended from captivity, the animals, which facilitated their journey, are also listed; both their number and that of the people are indicated in the prophetic book. For certainly there are many in the Church who are either slower in understanding or even carnal in mind, who nevertheless humbly submit to the spiritual teachers and diligently support the burdens of fraternal necessity. These, along with the other elect, are delivered from the confusion of diabolic captivity and strive towards the walls of the celestial city. Their number, as well as that of the more perfect ones, is preserved intact in the eternal memory of the inner witness. Thus, from the perspective of the holy universal Church, it is said to God: "Your eyes saw my imperfection, and all were written in Your book" (Psalms 139). And in another psalm: "You will save both men and animals, Lord; as You have multiplied Your mercies, O God" (Psalms 36). But immediately concerning the more perfect ones: "The sons of men shall hope under the shadow of Your wings" (Ibid.), etc. — Commentary on Ezra and Nehemiah