Greek δόξα (doxa)
Opinion or belief: the judgment the mind adds to what the criteria of truth report. Unlike the sensations, opinions can be true or false. An opinion is true if it is confirmed, or at least not contradicted, by the evidence of the senses, and false if it is contradicted or never confirmed. Errors, Epicurus said, always lie in opinion, never in sensation.
1. Key Texts
(1) Moreover, one must suppose that it is when something from external objects enters into us that we not only see but also think of their shapes. (2) For external objects would not imprint in us the nature of their colour and shape through the air which is between them and us, nor through rays or any kind of flow going from us to them, as well as by means of certain outlines coming from the objects to us, in colour and shape of sizes commensurate with our vision and our thought, moving swiftly; then, by the presentation of a single continuous outline, they produce an impression and the attendant sensation in virtue of their constant repetition from the object. (tr. Long & Sedley)