We've previously explored what it means to be human and what defines a person. Much of our understanding of personhood hinges on what we call character -- but what, exactly, is it? Here is an omnibus of definitions and insights from notable cross-disciplinary thinkers, from philosophy to neuroscience to literature, underpinning which is a shared sentiment that character is fluid and responsive to context, rather than a static and unflinching set of traits.

Philip K. Dick, from The Selected Letters of Philip K. Dick 1972-1973:

A person's authentic nature is a series of shifting, variegated planes that establish themselves as he relates to different people; it is created by and appears within the framework of his interpersonal relationships.

Biological anthropologist Helen Fisher in This Will Make You Smarter: New Scientific Concepts to Improve Your Thinking:

Personality is composed of two fundamentally different types of traits: those of 'character;' and those of 'temperament.' Your character traits stem from your experiences. Your childhood games; your family's interests and values; how people in your community express love and hate; what relatives and friends regard as courteous or perilous; how those around you worship; what they sing; when they laugh; how they make a living and relax: innumerable cultural forces build your unique set of character traits. The balance of your personality is your temperament, all the biologically based tendencies that contribute to your consistent patterns of feeling, thinking, and behaving. As Spanish philosopher, Jose Ortega y Gasset, put it, 'I am, plus my circumstances.' Temperament is the 'I am,' the foundation of who you are.

Psychologists Thomas Lewis, Fari Amini, and Richard Lannon in A General Theory of Love:

An infant's emotional scaffold provides for temperament and for innate abilities like reading facial expressions. Limbic contact with his parents hones that pluripotential structure into the template of emotional life -- the neural core of emotional identity. Once this quintessence is firm, we say that a person exists, and we can know the individuated attributes of his emotional self. Ongoing experience gradually transforms his neural configuration, changing him from who he was into who he is, one synapse at a time. Emotional identity drifts over a lifetime -- if fast and far enough, one might encounter a stranger's heart where a friend's or a lover's once dwelt.

Julian Baggini in The Ego Trick: In Search of the Self:

The topic of personal identity is strictly speaking nonexistent. It's important to recognize that we are not the kind of things that simply popped into existence at birth, continue to exist, the same thing, then die off the cliff edge or go into another realm. We are these very remarkably ordered collections of things. It is because we're so ordered that we are able to think of ourselves as being singular persons. But there is no singular person there, that means we're forever changing.

Ralph Waldo Emerson, quoted in A General Theory of Love:

Dream delivers us to dream, and there is no end to illusion. Life is a train of moods like a string of beads, and, as we pass through them, they prove to be many-colored lenses which paint the world their own hue.... Temperament is the iron wire on which the beads are strung.

William James, writing in The Principles of Psychology in 1890, sums it up perhaps best of all:

A man has as many social selves as there are individuals who recognize him.

This post also appears on Brain Pickings, an Atlantic partner site.