upon to form the module, and in accordance with this module the whole work is to be developed. Let the thickness of the columns at the bottom be two modules; an intercolumniation, five and a half modules; the height of a column, excluding the capital, fourteen modules; the capital, one module in height and two and one sixth modules in breadth. Let the modular proportions of the rest of the work be carried out as written in the fourth book in the case of temples.
4. But if the columns are to be Ionic, let the shaft, excluding base and capital, be divided into eight and one half parts, and let one of these be assigned to the thickness of a column. Let the base, including the plinth, be fixed at half the thickness, and let the proportions of the capital be as shown in the third book. If the column is to be Corinthian, let its shaft and base be proportioned as in the Ionic, but its capital, as has been written in the fourth book. In the stylobates, let the increase made there by means of the "scamilli impares" be taken from the description written above in the third book. Let the architraves, coronae, and all the rest be developed, in proportion to the columns, from what has been written in the foregoing books.
5. The space in the middle, between the colonnades and open to the sky, ought to be embellished with green things; for walking in the open air is very healthy, particularly for the eyes, since the refined and rarefied air that comes from green things, finding its way in because of the physical exercise, gives a clean-cut image, and, by clearing away the gross humours from the eyes, leaves the sight keen and the image distinct. Besides, as the body gets warm with exercise in walking, this air, by sucking out the humours from the frame, diminishes their superabundance, and disperses and thus reduces that superfluity which is more than the body can bear.
6. That this is so may be seen from the fact that misty vapours never arise from springs of water which are under cover, nor even from watery marshes which are underground; but in uncovered places which are open to the sky, when the rising
