According to Lucretius's frequent statements in his poem, the main purpose of the work was to free Gaius Memmius's mind of the supernatural and the fear of death. He attempts this by expounding the philosophical system of Epicurus, whom Lucretius glorifies as the hero of his epic poem. Lucretius identifies the supernatural with the notion that the gods/supernatural powers created our world or interfere with its operations in any way. He argues against fear of such gods by demonstrating through observations and argument that the operations of the world can be accounted for in terms of natural phenomena—the regular but purposeless motions and interactions of tiny atoms in empty space. He argues against the fear of death by stating that death is the dissipation of a being's material mind. Lucretius uses the analogy of a vessel, stating that the physical body is the vessel that holds both the mind (mens) and spirit (anima) of a human being. Neither the mind nor spirit can survive independent of the body. Thus Lucretius states that once the vessel (the body) shatters (dies) its contents (mind and spirit) can no longer exist. So, as a simple ceasing-to-be, death can be neither good nor bad for this being. Being completely devoid of sensation and thought, a dead person cannot miss being alive. According to Lucretius, fear of death is a projection of terrors experienced in life, of pain that only a living (intact) mind can feel. Lucretius also puts forward the 'symmetry argument' against the fear of death. In it, he says that people who fear the prospect of eternal non-existence after death should think back to the eternity of non-existence before their birth, which they probably do not fear.