The breadth of this doctrine lies in the fact that it is not absolutely forbidden to eat meat, as in all probability a fanatic, guided by his own wisdom, might have done; yet it must be observed, the implication is clear that it is possible for man to live without meat. Vegetarianism had been taught and practiced long before the days of Joseph Smith; but there had been no direct, positive proof that plants contain all the substances necessary for the sustenance of life. As stated above, it is now known that every class of nutritive substance found in meat is also found in plants. This is in full harmony with the implied meaning of Joseph Smith in the statement regarding the abstaining from meat. [Sidenote: The distinction between the values of grains is also scientific.] "All grain is ordained for the use of man and of beasts, to be the staff of life. * * * All grain is good for the food of man, as also the fruit of the vine, that which yieldeth fruit, whether in the ground or above the ground. Nevertheless, wheat for man, and corn for the ox, and oats for the horse, and rye for the fowls and for swine, and for all beasts of the field, and barley for all useful animals, and for mild drinks, as also other grain."[A] [Footnote A: Doctrine and Covenants, 89:14, 16 and 17.] The first part of this teaching, that all grain can be used by man and beast, corresponds to the earlier statement that all wholesome plants may be used by man. The latter part respecting the best grain for certain classes of animals, is of a different nature and merits special consideration. As already mentioned, all plants and plant parts contain four great groups of nutritive substances. The relative proportions of these grains are different in different plants or plant parts. For instance, wheat contains about 71.9 per cent of starch and sugar; corn, 70.2 per cent; oats, 59.7 per cent; rye, 72.5 per cent; and barley, 69.8 per cent. Wheat contains about 11.9 per cent of protein or the flesh-forming elements; corn, 11.4 per cent; oats, 11.8 per cent; rye, 10.6 per cent; and barley 12.4 per cent.[A] It has further been demonstrated that a man or beast doing heavy work, requires a larger proportion of starch and sugar in his dietary than does one which has less work to do. Likewise, different classes of animals require different proportions of the various nutrients, not only through life but at the various periods of their lives. This principle has been recognized so fully that during the last thirty-five or forty years the attention of experimenters has been directed toward the elucidation of laws which would make known the best combinations of foods for the various classes of farm animals, as well as for man. It must also be remarked that recent discoveries in science are showing more deep-seated differences in the composition of grains, than those here mentioned, as also corresponding differences in various classes of animals. Science will soon throw more light on