This article is the first of four that will be published on the subject of existential security in the National Security Studies. As it is defined by the authors, existential security is the conscious state of the limits of life (or the acceptance thereof) with physical and mental sufferings and other intellectually applicable dangers, in assessment of human transient nature (death). The end of life, considered as the source of trauma, stress, and anxiety, is born out of fear of nonexistence. Hence, the “existential security” is an offer to universalize the mental preparedness for this event, resting on the claims of proofs ranging from quantum physics to medicine and NDE (Near Death Experience). It seems through such perspective, that achieving the peace of mind on that matter is a better preparation than other, in view of death considered as material life’s end in hopeless predicament. The existential view of security is separate of theology, rejecting the one-dimensional interpretation of being, as it leans to, and still different from those propositions suggested by the quantum mechanics, neurobiology, psychiatry or noetics, and other conceptions, such as dualistic organization of being. In this view, the consciousness is in essence independent of brain (matter), as a life structure separate from the somatic covering, which does not have any individuality, since controlled by the mind (consciousness). However, the aim of the article is not to present the metaphysical proof of the existential security, since it rests on the presentation of various propositions of the philosophical mind. This is the reason why we present just general approaches towards the subject of death, in existential context of security, as seen in the ancient European philosophy. For this reason, the discussion focuses on problems of transience as explicitly described by orphic tradition, through the Pythagorean, Heraklitean, Socratic, Platonic, Aristotelian, Epicurean, Stoic and Neoplatonic philosophies.