4 I feel somewhat inclined myself to contribute a few hints towards the development of their system. For when I perceive that waters are in part fresh, such as fountains, rivers, showers, and so on, and in part salt; such as those in the sea, I reflect with myself that all such waters cannot be derived from her tears, inasmuch as these are of a saline quality only. It is clear, therefore, that the waters which are salt are alone those which are derived from her tears. But it is probable that she, in her intense agony and perplexity, was covered with perspiration. And hence, following out their notion, we may conceive that fountains and rivers, and all the fresh water in the world, are due to this source. For it is difficult, since we know that all tears are of the same quality, to believe that waters both salt and fresh proceeded from them. The more plausible supposition is, that some are from her tears, and some from her perspiration. And since there are also in the world certain waters which are hot and acrid in their nature, you must be left to guess their origin, how and whence. Such are some of the results of their hypothesis.
Source: Adversus haereses (New Advent)