Thomas Aquinas

The multiplicity of these senses does not produce equivocation or any other kind of multiplicity, seeing that these senses are not multiplied because one word signifies several things; but because the things signified by the words can themselves be types of other things. Thus in Holy Writ no confusion results, for all the senses are founded on one – the literal – from which alone can any argument be drawn, and not from those intended in allegory, as Augustine says. Nevertheless, nothing of Holy Scripture perishes on account of this, since nothing necessary to faith is contained under the spiritual sense which is not elsewhere put forward by the Scripture in its literal sense.

Summa Theologica 1.1.10 in McCartney, Let the Reader Understand (Bridge Point, 1994), 92.