Either we have time, or we have money. We spend our time earning money, then spend our money improving the quality of the time we have left over.

Alternatively, we can spend time saving money, by making instead of buying, or by shopping around. Or we can spend money saving time, by buying ready-cooked meals, or paying someone to make our purchases for us.

If we have no time to spend the money we earn, we've hit the edge of the continuum. Ditto if we have all the time in the world to starve, because we've got no money.

We can change our position on the continuum, by taking a job that pays less but is less time-consuming, or one that is more stressful, but gives us more money. These are the decisions that change our lives.