The thief who forces no locks

At an average annual inflation of 3 %, idle money loses half its purchasing power in about twenty-three years. Your account will keep showing the same figure; at the supermarket it will buy half. That's why they call it the silent thief: it forces no locks, it changes the value of what you keep.

The underlying mistake is looking at the number and not at what the number buys. Ten thousand euros under the mattress for twenty years are still ten thousand nominal euros, but their real buying power shrinks a little each year, without noise, without warning, without a single bill going missing.

The lesson isn't to take reckless risks; it's to understand that "doing nothing" with your money is also a decision with a cost. Standing still is moving too: downward.