Aurelius of Brittany greatly desires Dorigen, a married woman who has not seen her husband, the knight, for some years. Dorigen puts off Aurelius's advances by promising that she will yield when he clears the coast of Brittany of all its rocks. Eventually, a knowledgeable clerk calculates when an unusually high tide is due. Aurelius waits for that day to tell Dorigen he has fulfilled her conditions. Meanwhile, Dorigen's husband has returned.

Leaving the soap opera aspects for the English major, we note that Chaucer (who wrote a treatise on the astrolabe) spells out the astronomical calculation in far more detail than poetry or plot could possibly require.

His tables tolletanes forth he brought,
Ful wel corrected, ne ther lakked nought,
Neither his collect ne his expans yeeris,
Ne his rootes, ne his othere geeris,
As been his centris and his argumentz
And his proporcioneles convenientz
For his equacions in every thyng.
And by his eighte speere in his wirkyng
He knew ful wel how fer alnath was shove
For the heed of thilke fixe aries above,
That in the ninthe speere considered is;
Ful subtilly he kalkulled al this.
whan he hadde founde his firste mansioun,
He knew the remenaunt by propocioun,
And knew the arisyng of his moone weel,
And in whos face, and terme, and everydeel;
And knew ful weel the moones mansioun
Acordaunt to his operacioun,
And knew also his othere observaunces
For swiche illusiouns and swiche meschaunces

Probably the first work advocating effectively for gender equality among all classes of people. To comprehend the math / astronomy one should understand the rare astronomical configuration of December 1290 SEMICOLON the moon was at perigee while the earth was at perihelion and the three bodies were in a straight line. This results in the maximum high tides that the moon and sun together can generate. The elaborate description outlines the tools and math a medieval astrologer would use to make this calculation.