Very possibly this actually represents the main attitude of the Italian Renaissance artists toward architecture. They thought of it in its pictorial aspect and practised it primarily as an art of design. With them began the modern habit of conceiving a building primarily as a design on paper. It is an effect of what we have already mentioned--the separation of builder and designer that characterised the Italian Renaissance. Accordingly, while the following comparisons are based upon the principles that we have been adopting throughout this book, the reader should bear in mind the exception that has been taken to this method of judgment. =Palazzo Vecchio--Riccardi Palace.=--A good idea of the transition from the Gothic to the Early Renaissance in Florentine Architecture may be gained from a comparison of the =Palazzo Vecchio= and the =Riccardi Palace=. The former was built by Arnolfo di Cambio in 1298, as the Municipal Palace of the Podesta and Signoria. The Riccardi was erected in 1430 by Michelozzo for Cosimo I de’ Medici. While the Republic still survived as a name, he had usurped the actual power and occupied the Palazzo Vecchio until the completion of his own mansion, which was thenceforth to be the centre not only of the Medicean domination but also of its courtly splendour and liberal patronage of literature and art. Each edifice presents to the outside world a cubical mass, while the interior includes a cortile or open court. But the Vecchio is the severer in design, as befits Republican simplicity; it still has something of the character of a mediæval fortress, due largely to the heavy battlemented cornice that projects on massive corbels, with machicolations or openings in the floor of the gallery, from which defenders might drop missiles on an attacking force. A similar feature surmounted the original tower (for the present superstructure was added later)--a tower that was an additional source of defence as well as a lookout for the detection of fires or other local disturbances. It still served these purposes under the despotism of Cosimo; so that no tower was needed for his house. Meanwhile, he and his successors had ever to be on the watch against sudden alarms, so that it was admissible to preserve somewhat of the fortress character--massive masonry, with door and window openings, that might not be difficult to defend. On the other hand, it would be impolitic either to make the purpose of protection too apparent or to excite hostility by too lavish an appearance of grandeur on the exterior. Moderation must be the keynote of the design, and the facilities of luxurious living should be confined to the interior.