 Arcesilaus defends skeptical action also against Epicurean critics (Plutarch, Col. 1122A-d), again by showing on the basis of the Epicureans’ own premises that skeptical action is possible. Can the sceptic explain why, when leaving a room, they go through the door rather than running into the wall? Arcesilaus seems to have exploited the Epicurean view that, while all sense-perception is true, belief can introduce falsehood. Like the Epicurean, the skeptic can keep apart the perception and a view formed on its basis. By not assenting to the perception, thus adding belief (“here is the door”), the skeptic guards against the source of falsehood, namely belief. But a skeptic has perception of the door available to them, which is enough for not running into walls.