Internal valves, floats, and siphons hidden inside a vessel let it change its own behavior without a human touching it, so that a basin can refill itself or a lamp can trim its own wick as oil drops. The apparent intelligence lives in the concealed plumbing, not in any operator.
A siphon only discharges once the liquid level rises past the bend's crown, so sizing the siphon sets a threshold that delays and then suddenly releases flow. This converts a slow, continuous inflow into an abrupt, timed output event.
Many devices are engineered specifically to make observers expect one outcome (pour wine, get water; pour more, the flow stops) so that the hidden mechanism contradicts naive expectation. Here the point of the engineering is the surprise itself, treating the gap between appearance and inner workings as the deliverable.