in the sense of being connected as well as persistent, can provide the material of enduring opinion about public matters. There is a sense in which “opinion” rather than knowledge, even under the most favorable circumstances, is the proper term to use--namely, in the sense of judgment, estimate. For in its strict sense, knowledge can refer only to what _has_ happened and been done. What is still _to be_ done involves a forecast of a future still contingent, and cannot escape the liability to error in judgment involved in all anticipation of probabilities. There may well be honest divergence as to policies to be pursued, even when plans spring from knowledge of the same facts. But genuinely public policy cannot be generated unless it be informed by knowledge, and this knowledge does not exist except when there is systematic, thorough, and well-equipped search and record. Moreover, inquiry must be as nearly contemporaneous as possible; otherwise it is only of antiquarian interest. Knowledge of history is evidently necessary for connectedness of knowledge. But history which is not brought down close to the actual scene of events leaves a gap and exercises influence upon the formation of judgments about the public interest only by guess-work about intervening events. Here, only too conspicuously, is a limitation of the existing social sciences. Their material comes too late, too far after the event, to enter effectively into the formation of public opinion about the immediate public concern and what is to be done about it.