Ah! Here it is. The foursome division of spells by theme: mental, material, vital, and spiritual.
Paizo Playtest: All About Spells (Monday, April 16, 2018)
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Magical Traditions
For example, arcane magic blends material essence (the fundamental building blocks of all physical things) and mental essence (the building block of rational thoughts, logic, and memories). This means that arcane traditions share a lot in common with science, as arcane spellcasters tend to use logic and rational methods to categorize the magic inherent in the physical world around them. Divine magic is the exact opposite; it blends spiritual essence (the otherworldly building block of the immortal self) and vital essence (the universal life force that gives us instincts and intuition). This means that divine traditions are steeped in faith, the unseen, and belief in a power source from beyond the Material Plane. These ideas have led to some exciting new additions of spells into each tradition's repertoire.
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These four themes − mental, vital, material, and spiritual − are extremely powerful for organizing mechanics and narratives.
Every spell needs to have at least one of these four terms as a keyword descriptor.
The ‘mental’ spells mean the exact same thing as ‘psionic’. Consider using the term ‘psionic’ instead of ‘mental’ to tag these spells. Psionic spells include effects like charm, fear, dominate, suggest, but also all forms of divination along with luck and fate. Additionally psionic/mental includes all forms of force magic, including Telekinesis − Fly is nothing except telekinesing oneself − Magic Missile force damage, force constructs made out of force, and so on. Shapeshifting (aka psychometabolism) is really vital, but certain concepts will dabble into vital. Likewise, a pyrokineticist is really material/elemental. Teleportation (psychoportation) is spiritual spells.
Please, please, please, redefine Telekinesis as a mental/psionic *cantrip* whose strength heightens while advancing.
In the context of D&D spells, ‘material’ spells mostly means ‘elemental’ magic − earth (metal, crystal, etcetera), fire, air and water (together, air and water are weather magic). The flavor of lightning depends on whether one defines it as fire or air, or even an aspect of light (electromagnetic thus an aspect spiritual ether). The flavor of acid is difficult to decide − maybe fire (burn injury), water (corrosion), earth (chemicals). Probably make acid an aspect of fire to help fire diversify. Most forms of inorganic creations and animation is a material spell. Transmuting into elemental forms, like Gaseousform, Stoneskin, Ironbody, and so on, are material spells.
The ‘vital’ spells emphasize the living body, healing, regeneration, enhancement of the body, lifeforce, soul, animistic nature spirits, plants and animals, creation of items made from organic materials, like wood and leather, also poison. Vital especially includes organic lifeforms and substances, and ‘shapeshifting’ into animals and plants. (By contrast, ‘transmuting’ into inorganic elemental forms, like Stoneskin is a material spell.) The darkside of ‘vital’ is necromancy involving undead, vampirism, ghosts, and so on.
The ‘spiritual’ spells essentially involve the fifth element called Spirit (also called ether, quintessence, etcetera). Spirit is the stuff that the eternal soul and consciousness is made out of. As an element, it is identical with both light and void, space-time, and gravity. It extends to planar travel including both ethereal and astral destinations, as well as teleportation. As light, Spirit can include electromagnetism, and similar subatomic phenomena. Some tropes that arguably belong in the spiritual theme are assigned to one of the other three themes for the sake of flavor, such as divination and telekinesis belonging to psionic/mental. Essentially, the vital soul is made out of material ether which is psionic conscious. Spirit is a kind of magic that transcends, encompasses, and unifies the other three.
Certain spells describe more than one theme. For example, Wild Shape might specifically refer to taking on the mentality of a fierce animal, with such strong mindforce that body changes shape into the mental self identity. This (mythologically accurate) concept would cause the spell to get both tags, psionic/mental and vital. In this way, certain psion archetypes would access shapeshifting (psychometabolism) by means of such spells. Similarly, a spell like Control Sound normally relates to thunder, thus air-water elemental magic. But this specific spell might be understood as telekinetically manipulating vibrations according mental artistic esthetics and ambiance. In this way, the spell gains both the psionic/mental tag and elemental/material tag, thus certain bard archetypes would be able to access to dabble in this kind of sonic magic.
So arcane wizard normally accesses psionic/mental and material spells.
Bard accesses psionic/mental and vital spells.
Druid accesses vital and material spells.
Cleric accesses vital and spiritual spells.
Psion accesses psionic/mental spells but also spiritual.
Alchemist accesses material and spiritual spells.
And so on.
wizard opposite cleric
bard opposite alchemist
psion opposite druid
The spiritual classes: cleric, psion, and alchemist
The elemental/material classes: alchemist, druid, and wizard
The psionic/mental classes: psion, bard, and wizard
The vital/healing classes: druid, cleric, and bard