The preacher, the new age healer, and those who smoke too much weed are strangely united in the psychotic belief that their thinking can have an effect on objective reality. They are as it happens correct, but as it also happens all too frequently with far out ideas, they stopped thinking this through short of making sense.
There are many parallels between a brain and a plant: both rooted in one spot, mute, controlled by the chemicals they are full of, liquidly signalling to themselves. The alchemy of the brain, which commutes its thoughts into objective reality, is the same as the alchemy of the plant–namely, photosynthesis.
Exposed to an idea, the brain absorbs it, uses it to carry out a series of tiny structural and chemical changes within itself, and grows.
Of course the physical body can affect objective reality in a variety of ways, but it seems best to distinguish between these two kinds of changes.