The Purpose of Life
Maximum happiness is the only goal of living. It can be reached directly by seeking pleasure for pleasure, or indirectly by seeking knowledge and power as mediums for pleasure.
We may give ourselves up fully to pleasure sometimes, wherever pleasure takes us, without much thinking or resisting. Or we fulfill our duties first to secure our pleasure, by learning about the world and working on changing it. Enjoying, learning and workingópleasure, knowledge and powerócan be done separately, or, even better, simultaneously.
Enjoying ourselves wisely and powerfully helps us live and die in harmony with the world and become one with the infinite universe, bridging the gap between it and us, and avoiding any disharmony dampening our happiness. Since deep, long, safe, and new pleasures are not always available, we must move to find them, which requires extra effort, tension and pain sometimes. We move inward by learning, or outward by working, traveling, socializing, etc.
I. Seeking Pleasure
We make the best of our short existence simply to "feel happy"; any other purpose should serve that purpose. We should constantly seek utmost pleasure without having any guilt or confusion about that. The only sin we commit while we are alive, i.e. while we are temporarily conscious of existence, is to unnecessarily turn the short experience of life into a painful one.
II. Seeking Knowledge
We seek, accept and live the truth, to live and enjoy in the light, not in the darkness that we will eventually pass into anyway by death. Knowledge gives meaning, continuity and diversity to pleasure. We enjoy safe conscious pleasures more than those we can't trust or reason with. Truth is worth seeking wherever it takes us, although we will die and no longer can think of it. It's better to face the truth now than hide from it, for this is our only chance to know what life is all about.
III. Seeking Power
Knowledge without power is useless (feminine yin), power without knowledge is dangerous (masculine yang), and both are meaningless if not leading to pleasure. A ruler who seeks power without knowing what his subjects need is a prisoner of himself: he's like a child wanting a toy he doesn't know what to do with. People who seek power for itself, or for satisfying mindless animal pleasures, live a meaningless life with no purpose.
If we wish to extend our power, to control what is outside us, we must get out of ourselves first. If we can't change the world, we can still change ourselves, then we move to "outer levels." We have more power over the world when we get out of that prison of self, expanding in "time, space and person." Omnipotence is absolute power over space, time and other life forms; it has omnipresence, immortality, omniscience, and every absolute within, for on-demand use. We aspire to have it but we can never fully do (only a god can; and a deluded dictator/leader/boss thinks he can). Controlling time, space and life allows us:
We enjoy more the pleasures we control. A pleasure we can't control is appealing, teasing and curious, but less pleasurable because of the tension it creates: it's outside us, having its own will/rules/laws, not ours; there is always a possibility it turns against us, becoming a source of pain instead of pleasure. We feel more secure with the pleasures, partners, friends, colleagues or strangers we can influence. Yet, when such control hurts them, we become insecure again as they may "return the hurt." So we abandon some of our freedom, by sharing power together, controlling each other partially, mutually and willfully, so that they enjoy us too.
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Simply put, what gives meaning to life, distinguishing it from death, is doing while we are alive what we cannot do when we are dead. The greater the challenge, the deeper the meaning. There is no absolute meaning, because life has no absolute, well-measured existence. Leave absolutes for absolutists!
The three main goals of life, enjoying, understanding & changing life, shouldn't be taken from a secular perspective only, nor are they intended for someone and not the other. They are as much needed by the staunch secularist who rejects unscientific beliefs, and the zealous hedonist who lives for the here and now, as they are needed by the religious extremist who despises earthly pleasures altogether. To anyone with any belief, who came to understand the reality of life and its shortness, a purpose is a must. No matter how long it took to realize this, after a bad experience or a good one, through reading or meditation ... as intelligent beings we can't evade the question of "Why do we live?"
Secular & Religious
This is not the place to mention any belief-related purposes, because beliefs are personal and many. Rather, we focus on the "inherent" purposes every human naturally seeks, leading to common good/aspirations/purposes with other humans, uniting them together, to live in harmony, in happiness ... the ultimate purpose.
The various purposes each religion, culture and era has, vary widely. A monotheistic religion like Christianity, Islam or Judaism requires its believers to have extra purposes, usually by obeying certain commandments to achieve happiness in after-life; whereas, an atheistic religion like Buddhism is similar, except the reward is in living a happy life in a different future form, here on earth ... etc.
Both secular and religious people who go to extremes can miss the simple meaning of life:
Some secularists who focus on here-and-now pleasure only, which is not bad, miss a better experience of mixing their present with future pleasures to enjoy, foresee and live "in the mind" along with the present ones. Meanwhile, the religious who sacrifice the present for an unknown future are even worse than the secular who just ignore the future. By looking beyond the present and planning for the future, we help ourselves as well as those far-future generations, who may even overcome death and become immortal: we, the mortals, are helping them now find eternity.
On an intellectual level, some religionists seek infinity at the expense of truth, turning to superstition; whereas some secularists seek truth at the expense of infinity, turning to sensuality, self-centeredness and unimaginativeness. However, both seek pleasure, the primary goal of living.
It's unfair to consider the life of animals or people with no/different beliefs as meaningless, which is not. Without other animals and humans, dead or alive, we wouldn't be here now. The meaning of life of our ancestors is what gave them a reason to live, and gave continuity to life as a whole till it reached us. They passed their life experience along with the meaning it had for millions of years, on to us. Even animals and primitive humans are proven to have been happy and "curious" about discovering and changing the world, not just living to please their animal senses. The meaning of life is more simple and instinctive than complex or philosophical. It's an instinct we are born with, that we lose contact with sometimes, by confusion from "bad thinking" or other, less powerful instincts.
We are alive to make life a beautiful experience for us and other people, for our successors in the future whom we will never see, and for virtually everyone seeking the truth who still finds difficulty in accepting death as the inevitable end. We help others find a purpose, impartially, even when they are different from us, because by helping them we indirectly help ourselves. Putting the unknown, beliefs and traditions aside, we realize how all humans have common purposes. Focusing on those purposes, on what we share not what we differ on, helps humanity move forward and achieve future harmony and universal justice. Let's make this physical world we only have here a paradise, as long as we can breathe!
The meaning of life, for the atheist, theist, Hindu, Buddhist ... and virtually anyone, can equally get lost when individuals turn to nihilism, rejecting those basic simple goals of living they should've clung to, for the sake of "absolute" emptiness they wrongly believed they belong to, thus living a dull meaningless life and unconsciously hurrying their end, if not already, consciously, slowly killing themselves. In that case, as in some former communist regimes, or for newly converted atheists, where people "immediately" move from religious absolutism to atheistic absolutism, people's new, undefined, thus un-cherished goals begin to clash with one another, regressing to chaos instead of order (the ideal communist harmony some sought), missing and depriving their and others' life of meaning, of their simple, basic needs and pleasures.
Everyone wants pleasure, differently. Even masochists, sadists, anarchists, and people who take their own life are somehow happy with their choices. Pleasure comes down sometimes to a mere relief from pain, or from life. Or it turns against itself, by fighting all forms of pleasure, when they become constant reminders of pain, in which case, individuals destroy all good things, tearing down what they can't build up: health, money, friends, reputation, and self, theirs and others'.