“Debts to Nature” explores Greek myths about overreach and encroachment involving the operational deity the Greeks variously described as Potnia Therōn (“Mistress of the Animals”), the Great Goddess, or Mother of All, whose domain is Nature. It also concerns the implications of some sustainability principlesembedded and at work in Greek cult, especially acts of reciprocity and exchange in sacrificial ritual, which are ultimately explained by way of Albert Schweitzer’s philosophy of “Reverence for Life” (Ehrfurcht vor dem Leben). The poet Hesiod is proffered as an adherent to this kind of worldview and as an early systems thinker, deeply concerned about sustainable living.