[Illustration: PLATE IX. ARCHITECTURAL SKETCH BY OTTO RIETH] The most modern note yet sounded in business, in diplomacy, in social life, is expressed by the phrase, "Live openly!" From every quarter, in regard to every manner of human activity, has come the cry, "Let in the light!" By a physical correspondence not the result of coincidence, but of the operation of an occult law, we have, in a very real sense, let in the light. In buildings of the latest type devoted to large uses, there has been a general abandonment of that "cellular system" of many partitions which produced the pepper-box exterior, in favour of great rooms serving diverse functions lit by vast areas of glass. Although an increase of efficiency has dictated and determined these changes, this breaking down of barriers between human beings and their common sharing of the light of day in fuller measure, is a symbol of the growth of brotherhood, and the search, by the soul, for spiritual light. Now if this fellowship and this quest gain volume and intensity, its physical symbols are bound to multiply and find ever more perfect forms of manifestation. So both as a practical necessity and as a symbol the most pregnant and profound, we are likely to witness in architecture the development of the House of Light, particularly as human ingenuity has made this increasingly practicable. Glass is a product still undergoing development, as are also those devices of metal for holding it in position and making the joints weather tight. The accident and fire hazard has been largely overcome by protecting the structural parts, by the use of wire glass, and by other ingenious devices. The author has been informed on good authority that shortly before the outbreak of the war a glass had been invented abroad, and made commercially practicable, which shut out the heat rays, but admitted the light. The use of this glass would overcome the last difficulty--the equalization of temperatures--and might easily result in buildings of an entirely novel type, the approach to which is seen in the "pier and grill" style of exterior. This is being adopted not only for commercial buildings, but for others of widely different function, on account of its manifest advantages. Cass Gilbert's admirable studio apartment at 200 West Fifty-Seventh Street, New York, is a building of this type. In this seeking for sunlight in our cities, we will come to live on the roofs more and more--in summer in the free air, in winter under variformed shelters of glass. This tendency is already manifesting itself in those newest hotels whose roofs are gardens, convertible into skating ponds, with glazed belvideres for eating in all weathers. Nothing but ignorance and inanition stand in the way of utilization of waste roof spaces. People have lived on the roofs in the past, often enough, and will again. [Illustration: PLATE X. RODIN STUDIOS, 200 WEST 57TH STREET, NEW YORK]