From the age of seventeen to twenty, while in his Leyden home, we know little of the youth, save that he studied nature with loving fidelity, wandered over the low, picturesque country with its canal and windmills, and observed people and skies and landscapes. The first work attributed to Rembrandt was painted in 1627, when he was twenty years old, "St. Paul in Prison," showing care in detail and richness in color. During the next two years, he made etchings of himself and of his mother, who appears to have been his ideal. His first oil paintings were done in 1630; one, now lost, showing a philosopher in a grotto; and the "Bust of an Old Man," which, says Prof. John W. Mollett of France, in his Life of Rembrandt, "is the most interesting of all the Rembrandts in the Cassel Gallery, from the fact that it first displayed his knowledge of the great secret, which he subsequently so wonderfully developed, of concentrating light upon the heads of his portraits. He painted other old men's heads at the same date, and all are remarkable for indefatigable elaboration and care. In this same year, Rembrandt produced more than thirty etchings." After several years passed at Leyden, Rembrandt removed his studio to Amsterdam, a rich and flourishing city of one hundred thousand people at that time, whither his fame had preceded him. He hired apartments over a shop on the Bloemgracht, a quay in the western part of the city, where numerous pupils soon came to him, and commissions from the wealthy. One of his first principal works was "The Presentation in the Temple," now in the museum at the Hague. "The picture," says Mr. Sweetser, "presents a great temple interior, with groups of citizens and prelates, and, in the centre, massed under a bright light, the Holy Family, with the richly robed Simeon adoring the child Jesus. It is full of the strong shades and contrasting brightness of the new school of art, replete with poetic power and fresh personality, warm in golden lights, and in certain parts showing a rare minuteness of finish in detail. This subject was always a favorite with Rembrandt, and several other paintings thereof are preserved, together with numerous sketches and engravings, showing the venerable Simeon in the Temple at Jerusalem. "The 'Susannah' was executed during the same year, and is now at the Hague. The shrinking, naked figure of the fair bather, though lacking in statuesque beauty and symmetry, is thoroughly natural and tender, palpitating with life, and lighted with a warm and harmonious glow. This, also, was a favorite theme with Rembrandt, and conveniently replaced the Diana and Actæon of the classical painters with a subject not less alluring, and perhaps more permissible."