Saussure's family were Genevan patricians. His father, Nicolas de Saussure, was an agriculturist and author. His mother was sickly and so Saussure was brought up by his mother's sister and her husband the Genevan naturalist Charles Bonnet who sparked Horace-Bénédict's early interest in botany. After attending the Collège of his hometown, he completed his studies at the Geneva Academy in 1759 with a dissertation on heat (Dissertatio physica de igne). In 1760, he made the first of numerous trips to Chamonix Valley, at the foot of Mont Blanc, to collect plant specimens for the noted Swiss anatomist, physiologist and botanist Albrecht von Haller. In 1760, Saussure offered a reward to the first man to reach the summit of Mont Blanc. Inspired by his uncle, the naturalist Charles Bonnet, the young Saussure also did research on the physiology of plants and published Observations sur l'écorce des feuilles et des pétales (1762). The same year, at 22, he was elected professor of philosophy at the Academy of Geneva, where he lectured on physics one year, and on logic and metaphysics the next. He taught there until 1786, occasionally also lecturing on geography, geology, chemistry, and even astronomy.