The contemporary technique of the production of bottles foresees that some relief marks are imprinted on the bottom of them, usually simple casual relief drawings, which serve to prevent the glowing piece that has just come out of the machine that shapes the blob of glass, from sticking to the conveyor belt that takes the bottles to the next processing step.
The playing with the Leo bottle continues with the design on its bottom that refers explicitly to the so-called “knots of Da Vinci”, a name that derives indeed from vinci, or purple willow trees which give their name to Leonardo’s birthplace.
Several versions exist of these ornamental and arabesque motifs, among which a series of six prints made on his design by an engraver of Milan, and now preserved in the Ambrosian Library in Milan. Probably already conceived before him, and used for the decoration of embroidery, fabrics, leather, weapons or jewellery, they have been interpreted as a St. Andrew’s cross connected to the symbol of the infinity. The Da Vinci knots appear in many paintings by Leonardo (such as the Mona Lisa and the Lady with an ermine), had some success in the decorative arts of the 16th century, not only in the Lombard area, and became a much-used decorative motif in all central of Europe. Leonardo seems to identify himself with the infinite knot that has the shape of a continuous knot in the interweaving of the two signs of the infinity, as if to elevate the nodi vinciani as a symbol of secret knowledge.