53:26 · A sign for the alchemists' lapis philosophorum, the Stone of Wisdom, the prerequisite for the wished end result of the alchemical process. In this sign are combined the signs for the three most important substances used by the alchemist: sulphur, , salt, , and mercury, . Above the signs for these three substances the symbol , the structure of an alchemistic sign for year, , is holding its protective wings, and a vertical line connects it all.
    For the alchemists the Stone of Wisdom partook in the nature of the quinta essentia or quintessence, that is the fifth element after those of earth, water, air and fire. Therefore signs for the quintessence are somewhat synonymous with signs for the lapis philosophorum. The sign above in this group is one of the signs for quinta essentia.
    Lapis philosophorum could also be drawn .