One could point to no form of life that did not owe its existence to procreation by parents. They had fished the primeval slime out of the depth of the sea, and great had been the jubilation⁠—but the end of it all had been shame and confusion. For it turned out that they had mistaken a precipitate of sulphate of lime for protoplasm. But then, to avoid giving pause before a miracle⁠—for life that built itself up out of, and fell in decay into, the same sort of matter as inorganic nature, would have been, happening of itself, miraculous⁠—they were driven to believe in a spontaneous generation⁠—that is, in the emergence of the organic from the inorganic⁠—which was just as much of a miracle. Thus they went on, devising intermediate stages and transitions, assuming the existence of organisms which stood lower down than any yet known, but themselves had as forerunners still more primitive efforts of nature to achieve life: primitive forms of which no one would ever catch sight, for they were all of less than microscopic size, and previous to whose hypothetic existence the synthesis of protein compounds must already have taken place.