From The Warbourg Institute:
“The emblem, which appears above the door of the Institute and on all its publications, is taken from a woodcut in the edition of the De natura rerum of Isidore of Seville (560-636) printed at Augsburg in 1472. In that work it accompanies a quotation from the Hexameron of St Ambrose (III.iv.18) describing the interrelation of the four elements of which the world is made, with their two pairs of opposing qualities: hot and cold, moist and dry. Earth is linked to water by the common quality of coldness, water to air by the quality of moisture, air to fire by heat, and fire to earth by dryness. Following a doctrine that can be traced back to Hippocratic physiology, the tetragram adds the four seasons of the year and the four humours of man to complete the image of cosmic harmonies that both inspired and retarded the further search for natural laws.”