Fire making and joystick: what they have in common

1. Step 1. Fire making — evolved into — Lighter. A fire striker.
2. Step 2. Lighter — works like — Flintlock. The same way of striking a spark.
3. Step 3. Flintlock — has part — Spring. A mainspring.
4. Step 4. Spring — is part of — Joystick. They return the stick to the centre.

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