Galileo's Daughter

I particularly enjoyed Dava Sobel's previous book, Longitude, and have been very interested in Galileo (see Galileo's Dream), so it was an unexpected delight to find that back in 1999 Sobel had written this dual portrait of Galileo and his saintly oldest daughter, Virginia.

Virginia and her younger sister and brother were all born out of wedlock.  Because they were neither high born nor wealthy, Galileo could not arrange favorable marriages for his daughters and decided that the best chance they would have in life was to be entered into a convent - which, with help from highly placed patrons of Galileo, occurred before they were actually old enough to become Sisters.  The younger daughter, furious at her father and possibly having unrelated problems, subsequently had very little to do with Galileo.  In contrast, Virginia - later Suor Maria Celeste - was devoted to him, praying always on his behalf, preparing special treats and medicines for him, sewing his collars - and writing heartfelt letters to him.  Galileo described her to a friend as "a woman of exquisite mind, singular goodness, and most tenderly attached to me".  He kept all of her letters - approximately 120 - Sobel translated these and used them as a framework for much of the story of Galileo's life.   Sadly, none of Galileo's letters to Suor Maria Celeste have survived.

The book effectively describes Galileo's radically new approach to understanding the world  - that is, carrying out quantitative experiments and formulating the findings into laws rather than arguing from "first principles".  For this reason alone, he was vilified by adherents of Aristotle, "philosophers" who were accorded higher status and higher pay than mere "mathematicians" or "astronomers".   (Though astronomers, including Galileo, were frequently called upon by the aristocracy to create astrological forecasts).  One striking example of Galileo's experimental genius was illustrated by the astronomical discoveries he made with the telescope.  Galileo did not invent the telescope - but, having heard of it, or perhaps seen one, he carried out systematic experiments to determine the optimum shape and spacing of lenses.  This allowed him to construct telescopes with higher magnification and resolving power than anyone else.  With these, he famously discovered sunspots and how they illustrated the rotation of the sun, the phases of Venus, and the moons of Jupiter -all undermining the Aristotelian view of the celestial spheres as perfect objects that could not be flawed in any way - and also supporting the views of Copernicus, which later caused so much trouble for Galileo.

Interestingly, Galileo was a devout Catholic and believed there could be no real discrepancy between Catholic belief and the Copernican world view his discoveries supported.  He believed that God spoke to man in two ways, for one purpose.  The purpose was to induce men to believe and act properly so that they could enter the Kingdom of Heaven.  The two ways were scripture and the physical reality of the universe.  Scripture need not always be precisely consistent with physical reality, because its primary purpose was to guide people towards the holy light - and some simplification could aid this purpose.  But the physical world, also created by God, must necessarily be consistent with God's message to humanity.  Galileo hoped and urged his ecclesiastical friends to adopt this view - he felt that the Copernican view was certainly correct and that if the church declared it as heresy, the church would suffer when further experiments proved it to be true.  Pope Urban and others, however, believed scripture was paramount and to claim the universe to be other than described by scripture was heresy - and punishable.

In addition to his astonishing brilliance as a scientist, Galileo is shown in the book to be a practiced flatterer, adept at political intrigue, an outstanding prose stylist and....a doting and devoted father to Suor Maria Celeste.  I enjoyed this book immensely.