Note 61 — Chapter III
Fred Rothwell translation
Hellenbach, in his book, Magie der Zahlen, says regarding the number seven.
"The law governing the phenomena on which our knowledge is based decrees that the vibrations of sound and light regularly increase in number, that they are grouped in seven columns, and that the vibratory elements of each column have so close a relation to one another that not only can it be expressed in figures, but it is even confirmed by practice in music and chemistry.
"The fact that this variation and periodicity are governed by the number seven cannot be disputed; it is not a matter of chance: there is a cause and we ought to discover it."
In his table of the elements grouped according to atomic weight, Mendelejef also acknowledges that the number seven controls what he calls the Law of periodical function. He reaches conclusions similar to those of Hellenbach.
Dr. Laycock, in his Articles on the Periodicity of Vital Phenomena (Lancet) 1842, sums up as follows:—
"It is, I think, impossible to come to any less general conclusion than this, that, in animals, changes occur every 3-1/2, 7, 14, 21 or 28 days, or at some definite period of weeks."