Attention to specific issues at hand often leads us to overlook the function of the most noble of our faculties, but Locke believed that the operations of the human understanding are familiar to us all.
We employ ourselves in thinking, deciding, doing, and knowing all the time.
[Essay IV xvi 3-4] The great theme of the Essay, then, is that we ought not to expect to achieve knowledge beyond the relatively narrow confines of what is necessary or, at least, useful for the practical conduct of human life.
Although speculative knowledge of the essences of God, human beings, and material things exceeds the capacity of our cognitive faculties, according to Locke, we have no grounds for complaint.
Locke realized early on in his epistemological reflections that skeptical doubts often arise from unreasonable expectations about the degree of certainty it is possible for us to attain. 107] Academic philosophers have contributed to the problem by demanding demonstrative certainty of the speculative truth even in instances where we are unlikely to be able to achieve it.
But their demands for excessive precision in philosophical language lead only to pointless wrangling over the meanings of their terms, on Locke’s view.
What we require is not a detailed scientific explanation of the nature of the human mind, but rather a functional account of its operations in practice.
For that purpose, Locke supposed, we must pursue the “Historical, plain Method” of observing ourselves in the process of thinking and acting.
How short soever their Knowledge may come of an universal, or perfect Comprehension of whatsoever is, it yet secures their great Concernments, that they have Light enough to lead them to the Knowledge of their Maker, and the sight of their own Duties.
Men may find Matter sufficient to busy their Heads, and employ their Hands with Variety, Delight, and Satisfaction; if they will not boldly quarrel with their own Constitution, and throw away the Blessings their Hands are fill’d with, because they are not big enough to grasp every thing.