Several types of subject were recognised: "banketje" were "banquet pieces", "ontbijtjes" simpler "breakfast pieces". Virtually all still lifes had a moralistic message, usually concerning the brevity of life – this is known as the vanitas theme – implicit even in the absence of an obvious symbol like a skull, or less obvious one such as a half-peeled lemon (like life, sweet in appearance but bitter to taste). Flowers wilt and food decays, and silver is of no use to the soul. Nevertheless, the force of this message seems less powerful in the more elaborate pieces of the second half of the century.