Me and my father-in-law used to have a project we liked to work on together. It was with chickens. On several occasions we incubated some eggs. He had an incubator and I would care for it while the eggs were “cooking.”
One of the key elements in hatching those eggs was temperature control
If the temp. didn’t remain fairly constant we wouldn’t have good results. But another element was light. The incubator had two windows on top in order to let the light come in. If is was kept in complete darkness we wouldn’t have good results either.
Light gives life. Just like a garden, it needs light to produce.