The ‘Monas Hieroglyphica‘ (one glyph) is an emblem proposed originally by Athanasius Kircher and expanded on by Dr. John Dee for his sixteenth century treatise on the creation of a mystical symbolic language of the same name. The figure is based on the Egyptian Ankh and contains symbols of the seven planets/alchemical metals.
From: Alt Religion:
This occult symbol was created by John Dee and described in the Monas Hieroglyphica, or Hieroglyphic Monad, in 1564. The symbol is intended to represent the reality of the monad, a singular entity from which all material things are said to derive.
Summary of the Hieroglyphic Monad
Dee summarized his description of the glyph as such: "The Sun and the Moon of this Monad desire that the Elements in which the tenth proportion will flower, shall be separated, and this is done by the application of Fire."
The symbol is constructed from four distinct symbols: the astrological signs for the moon and the sun, the cross, and the zodiacal sign of Aries the ram, represented by the two semi-circles at the bottom of the glyph.
The Sun and Moon
The sun was generally considered the superior heavenly body in 16th century European astrology, a physical representation of God's divine and life-giving fire. Dee emphasizes the construction of the sun's symbol: a circular orbit around a central point that is the earth.
The moon, being of apparently equal size to the sun, also held particular esteem even though it was both feminine and occupied the lowest heavenly sphere. The moon, however, is dependent on the sun for it's light, and its appearance is constantly in flux through its shifting phases.
Finally, Dee turns to the authority of Hermes Trismegistus, mythological author of the hermetic texts, when he states:
"It is therefore clearly confirmed that the whole magistery depends upon the Sun and the Moon. Thrice Greatest Hermes has repeatedly told us this in affirming that the Sun is its father and the Moon is its mother: and we know truly that the red earth (terra lemnia) is nourished by the rays of the Moon and the Sun which exercise a singular influence upon it."
The cross represents a wide number of ideas. Dee explains that it represents the Ternary (group of three), being two lines and an intersecting point, which can represent body, mind, and spirit. The union of body and mind might just as easily be compared to the union of spiritual and physical, or of male and female, or of any number of other common occult dualities.
The cross also represents the Quaternary (group of four), for it is composed of four segments. In occult sciences, a group of four very commonly represents the four elements, and Dee gives considerable attention to this, describing them as "four straight lines running in four contrary directions from one common and indivisible point." The lines are not equal here because while every physical thing is composed of varying quantities of elements
Combining the Ternary and the Quaternary, you get a Septenary (group of seven). Groups of seven were of particular import to Dee and he used them often. Seven is the number of the planetary spheres, which were of central importance to any astrologer.
Finally, Dee, considers the Quaternary to be "an abridged or reduced form of the Decad," (group of 10), noting that 1+2+3+4=10 and that the Romans used a cross (specifically, an X) to represent the number 10.
The Sign of Aries
Each of the twelve zodiacal figures is traditionally associated with one of the four elements. Aries' element is fire (as is that of Leo and Sagittarius). Fire is the element of change, creation, and action, seen to bring about transformation in other things.
It may also be of note here that the stories of the Bible primarily occur during the Age of Aries, stretching roughly from the time of Abraham to the time of Jesus. (We currently are on the border between the ages of Pisces and Aquarius, with different astrological methods determining exact years somewhat differently)
Dee also notes that these four symbols, and parts of these four symbols, are the only symbols used to construct the astrological glyphs used to represent the other five planets (besides the sun and moon).