The Page is the apprentice; the Knight has learned it, mounted up, and is going full speed in one direction. All four Knights are on horseback — the only complete set in the deck that's in motion — and the difference is only the horse's pace: Wands' horse rearing, Swords' horse charging, Cups' horse walking, Pentacles' horse standing still.
Which shows the Knight's mechanism exactly: the element's nature decides how it pursues. Fire and air Knights are too fast, water and earth Knights too slow — all four are 'too much', and that's the essence of the rank: capable, aimed, and not yet able to regulate. So the Knight is the court card most likely to achieve something and most likely to crash.
Where you'll recognise it: periods of total commitment, being carried by a goal, and the moment afterward when you find the direction was off. Running well, a Knight is pure thrust: it takes things where no one else could. Stuck, its problem is accelerator without steering — speed isn't the issue, not watching the road is. What do the Queen and King have that it lacks? They know when not to move.
