In the science of plant symbols, not only the names, but the forms, perfumes, and properties of plants have to be considered, as well as the numerical arrangements of their parts. Thus of all sacred symbolical plants, those consisting of petals or calyx-sepals, or leaves, divided into the number Five, were formerly held in peculiar reverence, because among the races of antiquity five was for ages a sacred number. The reason of this is thus explained by Bunsen:--“It is well known,” he says, “that the numeral _one_, the undivided, the eternal, is placed in antithesis to all other numerals. The figure four included the perfect ten, as 1+2+3+4=10. So four represents the All of the universe. Now if we put these together, 4+1 will be the sign of the whole God-Universe.” _Three_ is a number sacred to the most ancient as well as modern worship. Pythagoras called it the perfect number, expressive of “beginning, middle, and end,” and therefore he made it a symbol of deity. _Three_ therefore plays its _rôle_ in plant symbology. Thus the _Emblica officinalis_, one of the sacred plants of India, was once the exclusive property of the priests, who kept its medicinal virtues secret: it was held in peculiar reverence because of its flowers possessing a six-parted calyx; three stamens, combined; three dichotomous styles; a fleshy fruit, tricoccous and six-seeded; these being all the sacred or double number of _Three_. In later days, the Shamrock or Trefoil, and the Pansy, or Herb Trinity, were regarded as symbolising the Trinity. Cruciform flowers are, at the present day, all regarded as of good omen, having been marked with the Sign of the Cross, and thus symbolising Redemption.