Repetition, not novelty, is the engine of expertise — but there's a specific kind of repetition that most high performers quietly abandon too early. The 13th-century Kabbalist Abraham Abulafia developed a practice he called 'combination of letters' (tzeruf): cycling through the same symbolic material over and over, not to extract new information but to exhaust the ordinary mind's grip on what it thought it already knew. His insight, which converges strikingly with what cognitive scientist Robert Kerr and his colleagues found studying contextual interference in skill acquisition, is that the brain's efficiency systems actively work against depth. Familiarity triggers a shortcut — the mind labels something 'known' and stops processing it fully, long before genuine mastery has set in. Abulafia's solution was to re-encounter the same material at a different speed, in a different order, under different conditions — not to learn something new but to break the premature closure that felt like knowing. The practical implication is this: pick one thing you consider yourself good at, and deliberately do it badly today — slower, in an unfamiliar order, with your non-dominant hand if that's relevant — not to build humility, but to revoke your brain's permission to coast.

Name one domain where you feel competent. Now describe, specifically, the last time you did something within that domain that genuinely surprised you about your own limitations.

Drawing from Jewish mystical philosophy (Kabbalah) synthesized with cognitive psychology of skill acquisition — Abraham Abulafia (Ḥayyei ha-Olam ha-Ba / Life of the World to Come, c. 1280 CE) synthesized with Robert Kerr and Bernard Booth (contextual interference effect, Journal of Motor Behavior, 1978)