Hegel was one of the philosophers, who seemingly (and also explicitly) paid only little attention to the conceptual problems of aetiology. The paper deals especially with those parts of his work, in which Hegel sheds light particularly on these problems. It examines a evaluates Hegel's conception of interconnection between entities such as reality, essence, necessity, appearance and causality (as well as causality and time). A special attention is paid to the question of "causa sui" as inherently related to the problem of mutual causation. The paper shows many methodological dangers as well as the lessons, we can still draw from Hegel's aetiological reflections.