The main traffic and commercial streets of the town should be wide and adorned with stately buildings; for in this way the visitors will get a more impressive idea of the town and often think that the other parts of it are equally beautiful. Cities do not have to be big sprawling metropolises or megalopolises to provide the leisure which produces the life of intellect. On the contrary, the two cities that have produced the greatest number of poets, painters, philosophers, scientists, historians, and architects have been relatively small cities by modern standards: Athens in the fourth and fifth centuries before Christ and Florence in Renaissance Italy. The city, in short, shows the good and evil in human nature in excess. Great cities have always been the melting-pots of races and of cultures. Out of the vivid and subtle interactions of which they have been the centers, there have come the newer breeds and the newer social types.