For the sense of boredom which it is impossible not to feel in a friend's company (when, that is to say, we must remain exposed on the surface of our consciousness, instead of pursuing our voyage of discovery into the depths) for those of us in whom the law of development is purely internal—that first impression of boredom our friendship impels us to correct when we are alone again, to recall with emotion the words uttered by our friend, to look upon them as a valuable addition to our substance, albeit we are not like buildings to which stones can be added from without, but like trees which draw from their own sap the knot that duly appears on their trunks, the spreading roof of their foliage.