The seven is the most natural expression of an element — which is why it's a perfect place to start. Sevens come after the six, and six is harmony: you've been through the changes and modifications of the five, and now things have settled. The seven is the natural purpose of an energy — what a suit does when it simply follows its own grain.
Seven of Wands
Wands are fire — spirit, passion, desire. (Wands tend toward career as the spirited passion of growing something, where pentacles are the physical labor of it.) The most natural expression of passion is to establish itself, enforce its will, make itself real. The figure holds the high ground against six staffs below — a reminder that passion should serve your higher self and drive off lower energies. When I pull it, it says: if you have an idea or a passion, do the natural thing it requires — get yourself out there, absorb the criticism, take your position — because the next card, the eight, is power and movement.
Seven of Cups
A figure gazes at seven cups, each holding something different — dreaming, possibility. Cups are the heart, emotional desire, longing, the subconscious, the watery level the brain doesn't directly steer. And isn't daydreaming the most natural thing for the heart to do — lost in what could be rather than what is? As a significator it can mean you're still in the planning or imagining stage; as a situation, that you're being told to pay attention to the possibilities.
Seven of Swords
Swords are air — mind, thoughts, intellectual programming. A man carries off a bunch of swords, leaving some behind, and that's one of the most quintessential natural processes of the mind: to take ideas. Most of what we think, we didn't invent — we were taught it, saw it, learned it from someone else's experience or story. People read this as theft, ideas stolen or not your own, and context can support that. But in general it's the mind doing what the mind does: taking what fits its paradigm — and remember the mind is ego, so that's not always what's good for you — and leaving the rest.
Seven of Pentacles
This one gets a bad rap, mostly from the face Pixie painted, and from the hermetic gloss of "shortened force" — he's so close to the reward but he's stopping. But sevens aren't about stopping; they're natural progression. Pentacles are earth — your work, health, body, bank account, the material world: the smells of your day, the food, the physical experiences. The pentacles here are growing, and seven is a decently high number from ace to ten — so this isn't failure. If you do the right labor, treat your body well, and work diligently, natural growth follows. You don't want to diet your way out of a health issue; you want to have planted the seeds long ago and now simply reap the benefit. I mainly read it as "shortened force" when it's reversed, or tied directly to a spiritual-alchemy reading about the person themselves.
The Chariot
Now the two major arcana sevens. The Chariot is the most natural of the first level of the major arcana. If you read the major arcana as the soul's journey through this sphere — the relationships, the matter, the fire and water and air — then seven is progress, pushing forward. Two sphinxes, one black and one white, pull in the same direction; the driver is ordained by the stars and the zodiac belt — this isn't reckless motion but confident progression aligned with the higher self. Move forward with celestial blessing. Very little the soul does isn't moving forward, moving back, or being disrupted — and the Chariot is the forward.
The Tower
And one more seven: the Tower, the sixteenth card — one plus six is seven. (This is one of the cards that made me adopt number reduction, because it bookends the Chariot so well.) Where the Chariot is "move forward with divine providence, go steamroll the enemy," the Tower is the opposite: a lightning bolt blasts the tower, knocks the golden crown off, throws people from the windows. A straight-up card of disruption — and when it appears, everyone reacts, for good reason. It comes much later in the soul's journey, and it's a major shift. But notice it's not the hand of hell reaching up to destroy the tower; it's lightning — light. The disruption is required, happening for a reason: maybe what you've built doesn't have divine providence. Disruption is okay — an important part — because look at the cards that come right after it. You weather the storm and get through it.
That's the six sevens of the Rider-Waite-Smith deck.