A remarkable statement of Calvin’s, from Institutes 4.14.18: speaking of the tree of knowledge and of the rainbow, Calvin says that these are given new being by the word of God that designates them as signs or testimonies. Then this Et antea quidem arbor erat arbor, arcus arcus; ubi inscripta fuerunt verbo Dei, indita est nova forma, ut inciperent esse quod prius non erat . That last clause translates, roughly, “when they have been inscribed by the word of God, a new form is introduced, that it might begin to be what at first it was not.” For Calvin, there is no “deeper” reality of things than the name God gives them. If he says “this is my body,” then it is impertinence to say “my chemical testing shows that it is still bread.” (Whether Calvin was always consistent with this insight is another question.)