It's obvious: «One man's meat is another man's poisson!»
Quest #1:Pleasure or Gratification is self-centric, not as a fault but unavoidably so, because looking inwards to oneself is needed to determine what actually does give you pleasure.
But surely: «The purpose of life is to live a life of purpose.»
Quest #2:Meaning or Purpose is socio-centric, not as a sign of goodness but unavoidably so, because you and your goal must look outwards to wider society with its values and potential for worthwhile projects; and also to find others who will join in.
Victor Frankl put it well: "Ultimately man should not ask what the meaning of his life is, but rather he must recognize that it is he who is asked."
Leo Rosten is down to earth: The purpose of life is not to be happy - but to matter, to be productive, to be useful, to have it make some difference that you have lived at all.
If we have a pattern here, which is likely because the taxonomy is characterised by oscillating dualities, then this next level will be self-centric.
To me, this next quest, for enlightenment, has the feeling of a quantum leap. Why?Not because it is uncommon, nor because it is poorly understood, nor because it is commonly promoted in spiritual contexts. It is because enlightenment is more than just self-centric, it is incipiently anti-social.
Enlightenment: A «Higher» Quest
Function: To know what is real, right and true. i.e. happiness depends on living a life built around the core value of truth.
But that is to court danger! Why? It should be immediately evident that this Quest can be construed as anti-social. Socrates, the quintessential Western seeker of Truth, was condemned to death for his «corrupting influence» on youth.
So: The purpose of life is «to know the human condition». This is primarily for your own benefit, even if others can also be helped.
As a pure state, Enlightenment-RH'3 is liberation from the fetters of illusion and delusion required by the hypocrisy and disinformation that characterize social life. Cartoonists capture the enlightened guru sitting on top of a mountain alone, but ready to answer the question about life asked by the man climbing up to him.
NOTE: All higher Quests can also be described as requiring Enlightenment, but they do not see happiness/meaning as rooted in just knowing what is true and real.
This Primal Quest-RH'L3 for human essences—truth, justice, virtue, freedom, reason &c.—is experienced as an all-consuming personal and totally practical urge. Enlightenment seems necessary to enjoy good health, to raise a family, to have friends, to work, to bear misfortune—so the urge to know and understand never ends. Why? Because, to the seeker, everyday life depends on freedom, responsibility, reason, truth, virtue &c, whose nature is not immediately obvious. These matters, it seems to the seeker, were never properly explained during socialization or even in higher education.
In that effort to know, the more that is known the more it is evident that you know so little, or even that you know nothing. Yet that awareness does not weaken your urge to know. Resolving any puzzle leads to the production of yet more puzzles. So the challenge that is being sought (and repeatedly met) regenerates and expands. It is natural and consistent that enlightenment is often equated with «a light amidst darkness», or «becoming absorbed in unknowing» or «knowing nothing».
Correspondence to Root Hierarchy: Knowing reality is impossible without Change-RHL3. Something that never changes, or is not part of a change or cannot generate experiential change within you, is not perceptible. The reality to be known via enlightenment-RH'L3 is our psychosocial reality: the ethical design of our personal lives, our families and our communities, as well as our institutions, organizations and governments. Given the imperfection of communal and organizational life, such knowledge invariably implies change—and that is why this Quest is regarded as anti-social by those in power.
If you think of enlightenment somewhat differently, perhaps in relation to spirituality (i.e. equal to liberation) or to science (i.e. equal to rejection of traditional beliefs), put your views in perspective by considering the confusions around enlightenment. Otherwise....