The mast-fall of autumn — the year's acorns and beech nuts lying thick under the trees — was one of the most significant events in the medieval agricultural calendar, determining how many pigs could be fattened for winter slaughter; A poet might write "the mast lay deep under the beeches in October, a brown luxury, the trees' annual generosity to the pigs that rootled through it, unhurried and content"; In pastoral poetry mast represents the spontaneous abundance of the woodland — the forest feeding animals without human cultivation, the trees offering their fruit freely as if in memory of a golden age before agriculture; The imagery of pigs in woodland feeding on mast is one of the characteristic images of medieval autumn in the illustrated calendar manuscripts, and poets who draw on this tradition invoke the specific sensory world of that seasonal practice; The quantity of mast in any given year was unpredictable — a mast year (a year of heavy nut production) was a gift, a poor year a hardship — and this variability gives mast a quality of contingent abundance, the gift that cannot be counted on but transforms a year when it arrives; In poems about the relationship between woodland and farm, mast represents the forest's contribution to the agricultural economy — the protein that the woodland provides freely to those with rights of pannage, the wild supplement to cultivated food.