Beautiful old out of print book in oversized format that you might be able to find at your local library. The writing is very dense, effortlessly wanders into Greek and Latin and has lots of references to the great works throughout. (Have your google, google translate, and google arts and culture apps at hand!) The large-format pictures -- at least half of the book by volume -- are what makes this book especially worthy of attention.
Years ago, I read Will Durant's The Renaissance: A History of Civilization in Italy from 1304-1576 A.D. and found it equally dense and sometimes hard to follow. But with patience and effort, small nuggets of truth and wisdom are slowly synthesized and distil upon the mind like dew drops.
In both reads, Erasmus stood out as a hero for me. "Christ has taught us to fight vice and not the Turks," he said. And, when invited by Zwingli to come live in Zurich, "I am extremely grateful for your affection and that of your city. But I desire to be a citizen of the world, a man of everywhere, or rather of nowhere." Chastel makes many references to In Praise of Folly, some funny, some profound. (Wisdom and humor . . . what a great pair of virtues.) Sympathetic of the Protestant reformers, but unwilling to go with them all the way, Erasmus has this wonderful temperance in an age of extremist views on both sides of the religious debate. In his Colloquium Religiosum, one of his protagonists says, "Saint Socrates, pray for us . . ." and "I find it difficult to believe that the blessed souls of Virgil and of Horace will not be saved." And in another place, "Perhaps the spirit of Christ is given more widely than we think."
This liberal universalism, willingness to question dogma, respect for 'pagan' classical antiquity, curiosity about any- and everything under the sun, levity, lightheartedness, permissive acceptance of pagans, Muslims, sinful popes, heathens, ignorant village cobblers, etc. was so much of what humanism was all about. And it was this liberal spirit of humanism that got us out of the middle ages and inspired the greatest works of art that have ever been produced.
Highlights for me from this book were all the funny grotesque figures that got squeezed into borders, friezes, paintings, cathedrals, etc. Bosch's Garden of Earthly Delights, Durer's Rhinoceros and Plaited Knot, Leonardo's horse drawings, Hans Daucher's Judgment of Paris panel, Benedetto da Maiano's Ceiling of the Palazzo Vecchio and oh, so many more!