An angel pours water between two cups, one foot in the stream and one on land. To move it without spilling you have to go slowly. The subject here is not balance so much as proportion.
Temperance usually appears where you need a ratio between two extremes — work and life, saving and spending, pressing and waiting. It does not ask you to pick one. It asks what mix this situation calls for. That does not mean the answer is the middle. It means there is a right proportion and it is specific to now.
It is also a card about time. Water takes a while to move between cups. Whether the subject is recovery, repairing a relationship, or getting good at something, it favours transferring all of it slowly over spilling half of it fast.
Reversed, it has gone all one way. Everything poured into work and nothing left elsewhere, or economising down past what you actually needed, or holding your tongue for months and then emptying it in one go. When this comes up inverted, the more useful question is what to refill rather than what to cut.
Take Temperance as 'restrain yourself' and half the card is gone. The image is two cups being poured into each other. It is not asking for less; it is asking for a ratio — closer to blending than to abstinence. It shows up often in front of someone trying to solve a problem by cutting one thing out completely.
With the Chariot it reads as an instruction to slow down. With the Devil it points at something already at an extreme. Temperance only gets specific once the neighbouring card tells you what is in excess.