Thought Transformation

A process transforms inputs into outputs. Thoughts are the outputs of the process called "thinking"; they are also its inputs. So thinking is the process of transforming thoughts into thoughts!

In principle, any existing thought may be involved (input) in the production of new or existing (output) thoughts. But if thoughts are only produced from thoughts, how can any thinking ever get started? Two possibilities are "innate thoughts" and "sensory inputs". In principle, innate thoughts can be generalised to initial internal conditions of the thinking entity, whereas sensory inputs can be generalised to impinging external factors. Thinking is the "magic" that moves the thinker from the initial conditions.

Sustaining the initial conditions, or zero movement, is a theoretical possibility. Whether this ought to be called thinking is debatable. But if there is a process that reproduces the pre-existing thoughts, I would consider it a mental (i.e. thinking) process.