The historical concept of a sabbatical is agricultural in nature. The land and people need rest periodically. After (usually) six years of work in an institution, you may be eligible for such a wonderful time. It is part of one’s employment contract (see Benefits; Negotiation) and is intended as an opportunity for rest and refreshment, a chance to write and retool. Sabbatical time clocks vary by institution. Additional leaves and shorter times between sabbaticals can occasionally be negotiated at the time of a job offer.