Main idea

If everything becomes a flash card, nothing is one any more. The deck draws its value not from what it contains taken one by one, but from the fact that getting in is hard: every card added dilutes the status of all the others.

Hence an order of magnitude, and it is low: a deck under two hundred cards remains a manipulable core of thought; five hundred is an upper limit beyond which suspicion is warranted. Having more than five hundred pillars is almost self-contradictory — a pillar is supposed to carry something, and a structure with that many of them is no longer a structure.

The result of overshooting isn't a deck that is too big, it's an object that has changed nature: a secondary note base, smaller than the first, with exactly the same problem. Rarity is part of the value, because creating a card doesn't say "this idea is interesting" but "this idea is structuring."

Layer added on 2026-09-20. The order of magnitude tightens in practice: two hundred cards as a personal limit, fewer than a hundred actually in play, because the entry criterion is demanding. The figure is borrowed and owned as such — Dunbar's number, transposed from social relationships to the ideas you want to maintain, supplies an intuition of boundedness and no proof at all. What the limit produces once reached stays open: deleting more, replacing, merging at the risk of weakening each card's own force.

Why it matters

It gives a refusal criterion you can invoke at the weakest moment, the one just after reading something very true. The right argument isn't that the idea is worthless, it's that letting it in costs the status of all the others.

And it says where to look to diagnose a setup that no longer works: volume, before content.

Nuances and limits

The figure is in no way a measurement. Two hundred is an order of magnitude of manipulability, not a demonstrated threshold, and what counts is the existence of a limit more than its value.

And a deck can be too small: a handful of cards don't structure a way of seeing, they caricature it.

Open questions

• Should the limit be a fixed ceiling, or simply the obligation to take a card out in order to let one in?