At furscht kracht of thunder

• at first crack of thunder: in Vico's philosophy, the first crack of thunder terrified primitive humans and drove them to seek shelter in caves, which led to the establishment of the first homes and families

• Furcht: (German) fear

• kracht: (German) crashes

• kracht: (Dutch) force, strength

• thunder: and, by association, lightning refer to Fire, the second of the four Classical Elements; Earth is alluded to in the preceding line and Air and Water in the two following lines