Moreover, such knowledge of persons is as solid as it is important. That two plus two make four cannot be gainsaid, and doubtless no other kinds of information can be quite so absolute as mathematical theorems. But when one thinks of a comrade, long loved and trusted until he is known through and through, for practical purposes one can think of nothing more stable than his knowledge of his friend. The plain fact is that we _do_ know people, know them well, and that this knowledge never has been or can be a matter of logical demonstration. By taking Arthur Hallam to pieces and analyzing him, the inductive mind might work out all the laws that are involved in Arthur Hallam's constitution; but that mind with all its knowledge would not know Arthur Hallam. Tennyson's "In Memoriam," however, makes clear that knowledge of a friend is not interdicted because scientific demonstration cannot supply it. Tennyson knew Hallam well, and this knowledge, far more solid and significant than most other information he possessed, was not achieved by grinding laws out of facts; it came, as all such knowledge comes, by faith. As one considers what this understanding of the personal world, seen with the open eyes of trust and loyalty, means to us, how assured it is, how it enriches and deepens life, he perceives that here at least faith is something far more than a stop-gap for ignorance, a dream, a fantasy. It is positively a pathway to truth. There is another realm where faith is our only way of dealing with reality; by it alone can we know _the possibilities of individuals and of society_. We are well assured now in the United States that the nation can be economically prosperous without slavery. But sixty years ago plenty of people were assured of the contrary, were convinced that if the abolitionists succeeded we could not economically endure. How did we come by this significant knowledge that the immoral system was dispensable? Not by logical demonstration. The economists of most of our universities logically demonstrated that slavery was essential. _Faith was the pathway to the truth._ Faith that a new order minus slavery was possible gained adherents, grew in certainty with access of new believers, fed its followers on hopes unrealized but passionately believed in, until _faith became experiment, and experiment became experience, and experience brought forth knowledge_. The nation trusted and tried. This is the only way to truth in the realm of moral possibilities. If the world were finished, its _i's_ all dotted and its _t's_ all crossed, we might exist on that sort of descriptive science that finds the facts and plots their laws. But the world is in the making; what is _actual_ is not quite so important to us as what is _possible_; we live, as Wordsworth sings, in "Hope that can never die, Effort and expectation and desire, And something evermore about to be."