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existence. The work is but unclean from one point of view; while engaged in it the workman is covered with dust and sand, but its aim is the highest degree of purity and cleanliness. At the second stage it was decided whether the smooth glass was to receive a concave or a convex form, and a concave or convex brass plate accordingly fixed on the cylinder; a screw was fixed alternately on either glass with pitch, and this by means of a peg turned round on the brass plate, on which the same movement as in the first stage was employed. Meanwhile the fine sand, now ground to polishing dust, must be spread on the plate by means of a brush, and water from the tin can near spurted out of the mouth on to the plate. After the two sides were so prepared the third stage was proceeded to; the brass plate was made hot, a drilled hole on the wrong side smeared with cement, covered on the right side with so-called caput mortuum (oxyd of iron), water being still sprinkled continually on it, and the glass thus polished. The glass having passed through the three stages of cutting, smoothing and polishing, so that neither crack nor flaw was discoverable, was perfect.

Spinoza soon mastered the mechanical difficulties, and the first glass that he perfected without extraneous aid from its roughest state to the satisfaction of the master made his eyes light up with pleasure. The sight of the perfected work was a