Here's why:

* Light-dependent reactions: The first stage of photosynthesis, known as the light-dependent reactions, directly uses light energy to convert light into chemical energy in the form of ATP and NADPH.

* Light-independent reactions (Calvin cycle): The second stage uses the chemical energy stored in ATP and NADPH to convert carbon dioxide into sugar (glucose).

So, while the Calvin cycle doesn't directly use light energy, it's still fundamentally powered by the light energy captured in the first stage.