[133] To a friend, who expressed surprise at her fluttering to and fro between mathematics and literature, she made a reply which deserves a place here, as it gives a better idea than anything else of the wonderful versatility of this gifted daughter of Russia. "I understand," she writes, "your surprise at my being able to busy myself simultaneously with literature and mathematics. Many who have never had an opportunity of knowing any more about mathematics confound it with arithmetic, and consider it an arid science. In reality, however, it is a science which requires a great amount of imagination, and one of the leading mathematicians of our century states the case quite correctly when he says that it is impossible to be a mathematician without being a poet in soul. Only, of course, in order to comprehend the accuracy of this definition, one must renounce the ancient prejudice that a poet must invent something which does not exist, that imagination and invention are identical. It seems to me that the poet has only to perceive that which others do not perceive, to look deeper than others look. And the mathematician must do the same thing. As for myself, all my life I have been unable to decide for which I had the greater inclination, mathematics or literature. As soon as my brain grows wearied of purely abstract speculations it immediately begins to incline to observations on life, to narrative, and _vice versa_, everything in life begins to appear insignificant and uninteresting, and only the eternal, immutable laws of science attract me. It is very possible that I should have accomplished more in either of these lines, if I had devoted myself exclusively to it; nevertheless, I cannot give up either of them completely." From Ellen Key's _Biography of the Duchess of Cajanello_, quoted in Anna Leffler's biography of Sonya Kovalevsky, ut sup, pp. 317-318. CHAPTER IV WOMEN IN ASTRONOMY Urania, the muse of astronomy, was a woman; and, although most of her devotees have been men, the number of the gentler sex who have achieved success in the cultivation of the science of the stars has been much larger than is usually supposed. There is reason to believe that woman's interest in astronomy dates back to early Egyptian and Babylonian times when the star-gazers in the fertile valley of the Nile and on the broad plains of Chaldea were so active, and when they made so many important discoveries respecting the laws and movements of the heavenly bodies. According to Plutarch, Aganice, the daughter of Sesostris, King of Egypt, tried to predict future events by the aid of celestial globes and by the study of the constellations. Her observations, however, were in the interests of astrology rather than of astronomy, as we now understand the science.