The English word enlightenment is a metaphor. A metaphor is a verbal (indeed notional) substitution, that is to say, a more acceptable or popular word (or phrase, hence notion, to wit, a euphemism operating as a placebo) is substituted for a less acceptable or unpopular word (hence notion). Some metaphors are false, indeed misleading, for instance like ‘sunrise’ or ‘all the world’s a stage.*
The metaphor (i.e. as false notion of) enlightenment suggests (the personal response to) a sudden (sometimes gradual) increase in freedom (i.e. as liberation from drag or impedance, hence dullness, darkness or heaviness (viz. depression), Sanskrit: moksha), the enlightenment effect being experienced as either a sense of brightness or of lightness (hence also of speed or elation).**
What the term enlightenment intends to describe, but disguises for reason of acceptable because pleasant distraction, is (the unpleasant knowledge of, hence uncomfortable biological truth about) a relative increase in personal survival capacity as basic biological function common to all biological units.
An increase in relative survival capacity, interpreted as an increase in freedom, is achieved if and when a (indeed any) bio-system decreases drag or hindrance (i.e. impedance ≈ darkness) in its drive to survival in any (world as) set of circumstances or conditions.
So it is that an increase in knowledge (for instance, the Buddhist samma-sambodhi), and, consequently a decrease in survival drag or impedance resulting from ignorance, is falsely described as enlightenment,*** the more knowledge acquired (i.e. the more ignorance removed) the fuller or brighter the enlightenment.
In a nutshell, the metaphor enlightenment suggests, in a popular roundabout way, an increase in response speed, thus an increase in survival capacity.
In fact, increased survival capacity and so enlightenment happens as the after-effect of problem solving.
And any problem solved will result in increased survival capacity, hence ‘speed’, hence enlightenment. Meaning that the (biological) enlightenment affect is the same for all enlightenments, differing only in intensity and which depends on the intensity or complexity (read: difficulty or importance, reflected in the amount of energy invested in the problem solving process) of the problem solved.
Therefore, taking a drink or a pee (thereby eliminating a drag on current survival performance) is a simple way of getting enlightened. Enlightenment (resulting from liberation) is, consequently, not a spiritual, mystical or religious experience. Enlightenment is a biological experience common to all. Obviously the hot shots of spiritual and religious communities make a big deal of enlightenment. They would, wouldn’t they!
The personal feed-back signal for an increase in relative survival capacity (thus enlightenment) in any set of circumstances (i.e. world) is happiness, i.e. elation. Unhappiness, i.e. depression, signals loss of relative survival capacity (thus endarkenment).
See my book ‘How to make and fake happiness’
*… A metaphor (so Wikipedia, with thanks) is a figure (hence fantasy) of speech that refers to something as being the same as another thing for rhetorical (popular) effect. It may provide clarity or identify hidden similarities between two ideas. (My addition) It may also be designed to disguise an unwelcome or uncomfortable truth.
**… Enlightenment is the word applied to a sudden energy surge, rush, release or increase. That energy surge happens if and when a problem, indeed any problem is solved, i.e. any obstacle overcome. The problem or obstacle binds energy during the removal attempts. When removal happens, the invested energy is released. For instance, if I’m carrying a heavy load and then set it down I feel lighter. If I suddenly understand something I feel brighter. Indeed if a kid is smart it’s called bright.
*** … What in English is described as ‘the Age of Enlightenment’ is described in French as ‘L’age de raison (i.e. reason)’ and in German as ‘das Zeitalter der Aufklaerung (meaning: clearing up)’. All three suggest that drag (to wit, lack of knowledge ≈ superior speed), experienced as darkness or heaviness, has been removed.