 Friedrich Welcker suggested that he symbolises the vain struggle of man in the pursuit of knowledge, and Salomon Reinach that his punishment is based on a picture in which Sisyphus was represented rolling a huge stone Acrocorinthus, symbolic of the labour and skill involved in the building of the Sisypheum.Albert Camus, in his 1942 essay "The Myth of Sisyphus", saw Sisyphus as personifying the absurdity of human life, but Camus concludes "one must imagine Sisyphus happy" as "The struggle itself towards the heights is enough to fill a man's heart.