Every part contains the whole in an infinite hierarchy of nested realities.
This is similar to the idea of a hologram wherein every component of the hologram contains the entire image. The principle of reflection is expressed through fractals and nested hierarchies in many areas of magical study.
For example every sign of the Zodiac has within it all twelve signs in some combination. Libra is Libra, distinct from its eleven companion signs, but within it are also the other signs, expressed under the influence of the parent sign, in this case Libra.
So there would be Aries within Libra, a more bold and confident manifestation of the sign, Cancer within Libra, a far more emotive expression of Libra, and so forth. This adds complexity and layering to the matter for sure, but also provides deeper understanding and more opportunity to assert magical influence.
The planets and elements also have nested hierarchies within them. This provides expressions like Venus in Saturn or fire of earth, etc.
The first term is the fractal and the second term is the parent power or energy. Thus with Venus in Saturn one would find emphasized Venusian qualities within the broader framework of Saturnine power. This could manifest as a potent attractive force working in tandem with laser-like focus, or restriction. With fire of earth there is perhaps an undertone of anger to the heavy somberness, or perhaps a hint of quickness to the set-in-stone stability of the overtone. This principle of reflection plays out to infinity, meaning ever deeper do the nested hierarchies unfold, so that water of fire of earth and even water of water of fire of earth, etc. are possible.
Such absurdities need never be considered as our ability to honestly conceptualize them is lacking. At the very most one might, given enough to drink or sufficient boredom, wish to play with the idea of deeper element of fractal of parent, i.e. water of fire of earth.
It is also possible and even useful to note the combining of hierarchical layering such as air of water with Mercury in Luna. This could be an expansive, emotional creativity expressed articulately yet intuitively.
Note it is proper to use “of” with nested elements, “in” with nested planets, and “with” when indicating element expressed by planet. Also “in” for planets within Zodiac signs and most other instances like Sephiroth within Sephiroth etc.