But today we have sung, “By the waters of Babylon we sat down and wept, when we remembered Sion.”
Observe “the waters of Babylon.” “The waters of Babylon” are all things which here are loved, and pass away. One man, for example, loves to practise husbandry, to grow rich thereby, to employ his mind therein, thence to gain pleasure: let him observe the issue, and see that what he has loved is not a foundation of Jerusalem, but a stream of Babylon. Another says, It is a grand thing to be a soldier: all husbandmen fear those who are soldiers.
But then other citizens of the holy Jerusalem, understanding their captivity, mark how the natural wishes and the various lusts of men hurry and drag them hither and thither, and drive them into the sea; they see this, and they throw not themselves into the waters of Babylon, but “sit down and weep,” either for those who are being carried away by them, or themselves whose deserts have placed them in Babylon, but sitting, that is, humbling themselves. O holy Sion, where all stands firm and nothing flows! Who has thrown us headlong into this? Why have we left your Founder and your society? Behold, placed where all things are flowing and gliding away, scarce one, if he can grasp the tree, shall be snatched from the stream and escape. Humbling ourselves then in our captivity, let us “sit by the waters of Babylon,” let us not dare to plunge ourselves in those streams, nor to be proud and lifted up in the evil and sadness of our captivity, but let us sit, and so weep. Let us sit “by” the waters, not beneath the waters, of Babylon; such be our humility, that it overwhelm us not. Sit “by” the waters, not “in” the waters, not “under” the waters; but yet sit, in humble fashion, talk not as you would in Jerusalem.
For many weep with the weeping of Babylon, because they rejoice also with the joy of Babylon. When men rejoice at gains and weep at losses, both are of Babylon. You ought to weep, but in the remembrance of Sion. If you weep in the remembrance of Sion, you ought to weep even when it is well with you in Babylon.
[Augustine, Expositions on the Psalms 137.1-4]
