The practical has no such guide or rule. We may be conscious that a practical problem exists, but we do not know what the problem is. We cannot be sure even of its subjective side––what it is we want or need. There is still less clarity on the objective side––what portion of the state of affairs is awry. These matters begin to emerge only as we examine the situation which seems to be wrong and begin to look, necessarily at random, for what is the matter. The problem slowly emerges, then, as we search for data, and conversely, the search for data is only gradually given direction by the slow formation of the problem.