The expenses of production being always greatest at first, it may happen that the home production, though really the most advantageous, may not become so until after a certain duration of pecuniary loss. . . . I have therefore conceded that in a new country a temporary protecting duty may sometimes be economically defensible; on condition, however, that it be strictly limited in point of time, and provision be made that during the latter part of its existence it be on a gradually decreasing scale. Such temporary protection is of the same nature as a patent, and should be governed by similar conditions.