The Solow model runs a whole economy as one quantity: capital per worker, k. Each year saving adds new machines — investment s·A·kα — while depreciation and a growing workforce erode the stock at rate (n+δ)·k.
Because production has diminishing returns (α = ⅓), the investment curve is concave: it begins above the straight break-even line, then flattens until the two cross. That crossing, k*, is the steady state — a stable attractor the economy returns to from any starting point.
A higher saving rate lifts the investment curve, so it crosses farther right at a richer k*. But that is a one-time gain in the level of income, not faster growth: once capital rests, output per worker stops rising. Here technology is frozen (A = 1, g = 0) to keep k* a true rest point.
The twist is welfare. What people enjoy is consumption, (1−s)·y, not output. It peaks when the saving rate equals capital's share, s = α = ⅓ — the Golden Rule. Save more than that and the nation is richer on paper yet poorer in the hand, because every extra machine is swallowed just maintaining a bloated capital stock.
Something in the simulation stopped unexpectedly — the lesson continues without it. You can move on; nothing you did was wrong.