16 of history's greatest philosophers reveal the secret to happiness

It's out of character for someone like Bertrand Russell, a lover of mathematics, science, and logic, to dabble in something so negotiable as happiness.

But his idea that happiness can be found in the surrender to visceral feelings of love rings true — and contemporary science seems to be on his side.

For Nietzsche, the famous mustachioed nihilist, happiness is a kind of control one has over their surroundings.

The German philosopher wrote frequently on the impacts that power (and a lack of power) can have on people's lived experiences. When people resist, they take back their agency. That sense of self can then turn into happiness.

For Socrates, one of the greatest ancient thinkers, happiness doesn't come from external rewards or accolades. It comes from the private, internal success people bestow upon themselves.

By paring down our needs, we can learn to appreciate simpler pleasures.

It's no surprise that Plato, Socrates' student, defines happiness like his teacher.

Plato's version of happiness is a form of personal growth. It's deriving satisfaction from achievements — running a faster mile, reading more books than last year — not for what those accomplishments can earn you.

By the time the message got to Aristotle, Plato's student, the idea of happiness had solidified into something we nurture on our own.

It's not a gift other people or things give to us, in other words. It's something we create from within and have a responsibility to protect.

John Stuart Mill was a titan of liberalism, perhaps its most important figure in history. He spread the gospel of liberty wherever he could.

When it came to happiness, he adopted the wisdom of the ancient Greeks. Instead of inundating his life with goods, Mill believed in utilitarianism. He believed in using things for a purpose, and if they served no purpose, he banished them from his life.

Confucius' sentiment about happiness has echoed through history in books such as "The Power of Positive Thinking" and recent research in cognitive behavioral therapy, which seeks to help people see the connections between their thoughts, feelings, and behaviors.

According to a Confucian mindset, happiness is a self-fulfilling prophecy that replicates itself the more we find reasons for its existence.

Beloved by contemporary philosophy nerds like the investor Nassim Taleb and marketing whiz Ryan Holiday, the Stoic philosopher firmly believed in what psychologists would now call the "locus of control."

For some people, the locus lives externally. They feel like outside forces guide their actions. For others (in Seneca's mind, the happy ones), the locus lives within.

Translated simply as "Old Man," nobody is quite sure who Lao Tzu really was. But the figure's wisdom on living in the moment has transcended millennia.

And psychologists uphold its benefits.

Some research suggests people report the greatest happiness when they are engaged in things that require their full and present attention: good conversation, creative tasks, or sex.

The most famous Confucian thinker aside from Confucius himself, Mencius believed that humans are naturally good-natured and can become more personally fulfilled through education and self-discipline.

However, he also believed people have the power to ruin their potential. The difference may simply come down to people's decision to cultivate joy from within.

Before there was the stellar mash-up Twitter account Kim Kierkegaardashian, there was the Danish philosopher who inspired it.

Kierkegaard was of the mind that happiness comes from being present in the moment and enjoying the ride. Once we stop turning our circumstances into problems and start thinking of them as experiences, we can derive satisfaction from them.

Perhaps unsurprisingly, the transcendentalist author and advocate for civil disobedience took a passive approach to happiness.

As he detailed in "Walden," Thoreau preferred to break convention. He avoided habit. Perhaps through the commitment to randomness, he thought, he could find some larger, more cosmic sense of happiness.

The idea aligns nicely with other thinkers' message to live in the moment.

The French philosopher takes a different approach to happiness compared to Socrates' theory that the unexamined life is not worth living.

For Camus, an absurdist, happiness was a pretty bleak life goal. He instead preferred to live meaningfully in the moment and not dwell too much on long-term pursuits, as reflected in his most famous work "The Myth of Sisyphus."

Around the time Aristotle and Plato were dropping their knowledge bombs, Epicurus was also sharing his thoughts on how to live the happy life. Material pleasures held little importance for him; rather, he advocated the pursuit of wisdom as a way to profound joy.

An important ingredient for Epicurus in all this was friendship. He believed shared wisdom was stronger and more valuable than being a wise loner.

A feminist, novelist, and political philosopher, de Beauvoir married much of her existential beliefs with those of her political ones.

She sought happiness in notions of "freedom," particularly as women struggled to distinguish themselves as individuals, not second-class citizens to men. Her famous book "The Second Sex" addresses such frustrations.