I have found a wonderful 16th Century Christmas Carol that is quite secular but the words do not make good sense to me. If someone could shed some light, I would be appreciative.

The lyrics are as follows with my questions all parenthesized.

Christmas Hath Made and End – Essex's Last Farewell
(16th Century Carol from the Virginal Book of Elizabeth Rogers)

Christmas hath made an end, Well a day, well a day,
Which was my dearest friend, More is the pity.(More is the pity?)
For with a heavy heart must I from thee depart.
To follow plough and cart All the year after.

Lent is fast coming on, … That loves not any one, …
For I doubt both my cheeks will look thin eating leeks;
Wise is he then that seeks for a friend in a corner.(friend in a corner?)

All our good cheer is gone. … And turned to a bone, …(turned to a bone?)
In my good master's house I shall eat no more souce (southern potted meat?)
Then give me one carouse, Gentle, kind butler. (one carouse?)

It grieves me to the heart, … From my friend to depart, …
Christmas I mean, 'tis thee that thus forsaketh me,
Yet till one hour I see will I be merry.