Consciousness: Knowing With Yourself
The word *consciousness* is built from two Latin pieces: *con-* (together, with) and *scīre* (to know). At its root, consciousness means "knowing-with" — specifically, knowing with yourself. It is the word the English language invented to describe the experience of being aware that you are aware.
The Latin Foundation
Latin *conscientia* originally meant shared knowledge — the kind of knowing you have when you are "in on" something with someone else. *Conscius* described a person who was privy to a secret, a co-knower. The prefix *con-* (with, together) combined with *scīre* (to know) to produce a word about mutual awareness.
But Latin already contained the seed of the inward turn. *Conscientia* could also mean knowledge shared with oneself — an inner witness. This is the sense that produced English *conscience* (moral self-awareness) and eventually *consciousness* (awareness itself).
Locke's Revolution
The word *conscious* entered English around the 1590s, but it was the philosopher John Locke who transformed its meaning. In his *Essay Concerning Human Understanding* (1690), Locke defined consciousness as "the perception of what passes in a man's own mind." This was revolutionary — he made consciousness not just a state of being awake, but the defining feature of personal identity. You are you, Locke argued, because you are conscious of being you.
The Science Connection
The Latin root *scīre* (to know) also produced *scientia* — knowledge, which became English *science*. Consciousness and science are etymological siblings: both are forms of knowing. One looks inward, the other outward. The hardest problem in modern science — explaining consciousness — is, etymologically, the problem of one kind of knowing trying to explain another.