2 There are some, then, likely to object to this work of mine, because they have failed to understand the rules here laid down. Others, again, will think that I have spent my labor to no purpose, because, though they understand the rules, yet in their attempts to apply them and to interpret Scripture by them, they have failed to clear up the point they wish cleared up; and these, because they have received no assistance from this work themselves, will give it as their opinion that it can be of no use to anybody. There is a third class of objectors who either really do understand Scripture well, or think they do, and who, because they know (or imagine) that they have attained a certain power of interpreting the sacred books without reading any directions of the kind that I propose to lay down here, will cry out that such rules are not necessary for any one, but that everything rightly done towards clearing up the obscurities of Scripture could be better done by the unassisted grace of God.
Source: Christian Doctrine (New Advent)