The Seven Lamps of Architecture  by John Ruskin - Book-length essay on architecture by John Ruskin, published in 1849. According to Ruskin, the leading principles of architecture are the "lamps" of Sacrifice, Truth, Power, Beauty, Life, Memory, and Obedience. The noblest style of architecture was   Gothic, but in time medieval architecture had lost the power to resist innovation. This loss of vitality was the result of the spiritual decline of Christianity during the materialistic Renaissance.

The Genius of John Ruskin : Selections from His Writings (Victorian Literature and Culture Series) by John Ruskin, John D. Rosenberg (Editor), Herbert F. Tucker
Highly acclaimed anthology of John Ruskin, this book is made out of 39 vols Library Edition of John Ruskin's works,  supported by 5 pillars--art, architecture, society, solitude and self and compiled chronologically.In the introduction, Herbert Tucker estimates this book as a classic anthology. It is followed by Rosenberg's preface, and before each  section mentioned above is his own explanatory comment. This is extremely superb in style as well as contents. At the end of the book is a new bibliography, to some of which entries brief comments are added. As Ruskin's writings,  especially those in early years, are not easy to read, this book is priceless. Among relatively rare entries are "Traffic"  in The Clown of Wild Olive, "Athena Keramitis" in Queen of the Air, and "Essay I" in Fiction Fair and Foul.Compared with the previous anthology by Kenneth Clark, "Ruskin Today", this one is inferior in variety but far superior in amount. Now we have the Ruskin's Complete Works in one CD-ROM, but it cannot be read, say, in a train or bed unless printed out. Concisely selected, this book is, I think, quite valuable when kept by your side.