Seventh-year sabbatical.

I've always just taken for granted that academicians have a special perk not found in most other jobs -- a year-long paid leave from classroom and administrative responsibilities, to produce research. The seventh-year sabbatical.

Only today did I realize that the tradition has its roots in the Jewish idea of the seventh-year jubilee: a sabbath of complete rest taken every seven years, after six years of harvesting.

Interesting.