In subjects of general interest, the task of defining terms should consist in choosing amongst the various interpretations which have gradually become attached to certain words, not always that one which is most intimately or etymologically connected with the primary root, but that which would indicate an important practical difference. Yet by an unforeseen misfortune, the daily necessity comes before us of using words whose meaning has never been clearly defined, so that at no time has one meaning prevailed more than another; this is especially the case with words connected with religion, faith, and objects of belief, which each one understands after his own manner. In our days the possibility of an agreement between religion and science is often debated; how can we enter on the discussion without being quite clear as to what religion is? According to some it is simply the feeling of love for God; according to others it is the expression of our faith under the form of acts of worship, acts of charity, or perhaps the holding of certain dogmas. The same holds good with that which we call faith, and which is often a feeling of confidence--not always the result of thought--in the faith of those surrounding us. Some give the name of faith to that enthusiasm which has sufficed to cause men joyfully to meet martyrdom; others apply it to the confidence with which the wise men followed the guiding of the star, when it indicated the road they should follow. Faith is only worthy of the name when it can be said to be a reasonable faith, and thus accounting for its existence. If we are not amongst the number of those who can give a reason for the faith that is in them, we must take care that credulity does not glide in before we are aware of its approach; it arises from a weakness of the mind and is compatible with a tranquillity that differs very widely from peace; and when once mistress of the situation, it increases, and occupies it. A wise Arab well said, “He who builds his house on human credulity builds on a rock.” “Abstract,” this word which we can trace back to Aristotle, has an interesting history. Aristotle used it at first to characterise the creation of a work of art; the sculptor carves out of a block of marble the statue of a man or of a woman, rejecting the chips and dust which serve no purpose. Afterwards Aristotle applied this same word to an idea which an accurate thinker forms, giving it a suitable shape, and separating it from all accidental thoughts that may have surrounded it; that done, what remains is an abstract idea. Aristotle has so well explained the meaning of abstract, that if our logicians had simply spoken of _concrete_ as that which is non-abstract, all the world would more readily have understood the meaning of the word--concrete.