Axiology (from Greek: άξιος, axios, "value, worth"; and λόγος, logos, "speech" lit. "to talk about the value") is the study of quality or value. It is often thought to include ethics and aesthetics[citation needed] — philosophical fields that depend crucially on notions of value — and sometimes it is held to lay the groundwork for these fields, and thus to be similar to value theory and meta-ethics.
One area in which research continues to be pursued is so-called formal axiology, or the attempt to lay out principles regarding value with mathematical rigor.