Talking with my three year old engineer: I realized that the greatest achievement of the humanity after controlling the fire and inventing the wheel is the harnessing of electrons. Maxwell equations in a differential form rules. Explaining how electrons wait at the gate (power switch), and that some gates opens wide and some can be opened a bit (like light bulb power switch vs stand mixer speed switch). Amazing he could understand this metaphor. But how he knew the existence of electrons - no idea.

God said four Maxwell equations in differential form and there was light. Without it we would watch TV by candlelight.