Theano (Greek: Θεανώ; 6th-century BC) is the name given to perhaps two Pythagorean philosophers. She has been called the pupil, daughter and wife of Pythagoras, although others made her the wife of Brontinus. Her place of birth and the identity of her father are just as uncertain, leading some authors to suggest that there was more than one person whose details have become merged (these are sometimes referred to as Theano I and Theano II). A few fragments and letters ascribed to her have survived which are of uncertain authorship.
Little is known about the life of Theano, and the ancient sources are confused. According to one tradition, she came from Crete and was the daughter of Pythonax, but others said she came from Croton and was the daughter of Brontinus. She was said by many to have been the wife of Pythagoras, although another tradition made her the wife of Brontinus. Iamblichus, in an attempt to resolve the confusion, refers to Deino as the wife of Brontinus.
The writings attributed to Theano were: Pythagorean Apophthegms, Female Advice, On Virtue, On Piety, On Pythagoras, Philosophical Commentaries, and Letters. None of these writing have survived except a few fragments and letters of uncertain authorship. Attempts have been made to assign some of these fragments and letters to the original Theano (Theano I) and some to a later Theano (Theano II), but it is likely that they are all pseudonymous fictions of later writers, which attempt to apply Pythagorean philosophy to a woman's life. The surviving fragment of On Piety concerns a Pythagorean analogy between numbers and objects; the various surviving letters deal with domestic concerns: how a woman should bring up children, how she should treat servants, and how she should behave virtuously towards her husband.
- Plant, Ian Michael (2004). Women writers of ancient Greece and Rome: an anthology. University of Oklahoma Press. p. 68. ISBN 978-0-8061-3621-9.
- Porphyry, Life of Pythagoras, 4
- Suda, Theano θ84
- Diogenes Laërtius, viii. 42-3
- Suda, Pythagoras π3120
- Suda, Theano θ83
- Iamblichus, On the Pythagorean Life, 132
- Ian Michael Plant, (2004), Women writers of ancient Greece and Rome: an anthology, page 69. University of Oklahoma Press
- Mary Ellen Waithe, A History of Women Philosophers. Volume 1, 600 BC-500 AD. Springer
- Voula Lambropoulou, Some Pythagorean female virtues, in Richard Hawley, Barbara Levick, (1995), Women in antiquity: new assessments, page 133. Routledge
- Mary Ritter Beard, (1931), On understanding women, page 139. See also: Mary Ritter Beard, (1946), Woman as force in history: a study in traditions and realities, page 314
Further reading 
- Kai Brodersen, Christoph M. Wieland, (2010), Theano: Briefe einer antiken Philosophin. Greek/German. Reclams Universal-Bibliothek 18787, Stuttgart. ISBN 978-3-15-018787-6