From the Lives of the Brethren:
The Chancellor of the University in Paris, having decreed [February 1256] that this same Brother Thomas should maintain his thesis publicly next day for the doctorate, that same night this brother beheld a figure come and stand before him with an open book in which were written the words:
“Thou waterest the hills from above, the earth shall be filled with the fruit of thy works” (Ps. ciii 13).
He therefore chose them for the text of his thesis.