In discussing questions of this kind two rules are to be observed, as Augustine teaches. The first is, to hold the truth of Scripture without wavering. The second is that since Holy Scripture can be explained in a multiplicity of senses, one should adhere to a particular explanation, only in such measure as to be ready to abandon it, if it be proved with certainty to be false; lest Holy Scripture be exposed to the ridicule of unbelieres, and obstacles be placed to their believing.
The context? ”Whether the Firmament was Made on the Second Day”. (It was.)