midnight
From one o'clock until three he enjoyed a siesta . At three he resumed his studies , which continued without interruption until six when he partook of a second meal . At seven he took another stroll in the village or by the seashore and remained out of doors until nine . He then withdrew into his study , and at midnight went to bed . It was , perhaps , the extreme regularity of his life , combined with the strict diet which he observed , that accounted for his good health . This day was his seventieth birthday , and his body was as vigorous and his mind as alert as they had been in his fortieth year . His thick hair and beard were scarcely grey , and the wrinkles on his white , thoughtful face were rare .