The question of the reality of the soul and its distinction from the body is among the most important problems of philosophy, for with it is bound up the doctrine of a future life.  The soul may be defined as the ultimate internal principle by which we think, feel, and will, and by which our bodies are animated.  The term "mind" usually denotes this principle as the subject of our conscious states, while "soul" denotes the source of our vegetative activities as well.  If there is life after death, the agent of our vital activities must be capable of an existence separate from the body.  The belief in an active principle in some sense distinct from the body is inference from the observed facts of life.  The lowest savages arrive at the concept of the soul almost without reflection, certainly without any severe mental effort.  The mysteries of birth and death, the lapse of conscious life during sleep, even the most common operations of imagination and memory, which abstract a man from his bodily presence even while awake; all such facts suggest the existence of something besides the visible organism. An existence not entirely defined by the material and to a large extent independent of it, leading a life of its own.  In the psychology of the savage, the soul is often represented as actually migrating to and fro during dreams and trances, and after death haunting the neighborhood of its body.  Nearly always it is figured as something extremely volatile, a perfume or a breath. 
In Greece, the heartland of our ancient philosophers, the first essays of philosophy took a positive and somewhat materialistic direction, inherited from the pre-philosophic age, from Homer and the early Greek religion.  In Homer, while the distinction of soul and body is recognized, the soul is hardly conceived as possessing a substantial existence of its own. Severed from the body, it is a mere shadow, incapable of energetic life.  Other philosophers described the soul's nature in terms of substance.  Anaximander gives it an aeriform constitution, Heraclitus describes it as a fire.  The fundamental thought is the same.  The soul is the nourishing agent which imparts heat, life, sense, and intelligence to all things in their several degrees and kinds.  The Pythagoreans taught that the soul is a harmony, its essence consisting in those perfect mathematical ratios which are the law of the universe and the music of the heavenly spheres.  All these early theories were cosmological rather than psychological in character.  Theology, physics, and mental science were not as yet distinguished. 
	In the "Timaeus" (p. 30), one of Plato's writings, we find an account derived from Pythagorean sources of the origin of the soul.  First the world-soul is created according to the laws of mathematical symmetry and musical harmony.  It is composed of two elements, one an element of "sameness", corresponding to the universal and intelligible order of truth, and the other an element of distinction or "otherness", corresponding to the world of sensible and particular existences.  The individual human soul is constructed on the same plan.  
The Stoics taught that all existence is material, and described the soul as "a breath pervading the body".  They also called it Divine, a particle of God; it was composed of the most refined and ethereal matter. They denied absolute immortality; relative immortality, ending with the universal conflagration and destruction of all things, some of them admitted in the case of the wise man.  Yet many others, such as Panaetius and Posidonius, denied even this, arguing that, as "the soul began with the body, so it must end with it". 
		With Socrates came a revolution in all manners of thought.  As, perhaps, the most influential of philosophers, and also one of the best known, it is truly unfortunate he left the future so little of his theories.  Only through the writings of his students have we any idea of his philosophy.  In the writing of Plato much thought is given to the concept of the human soul.  Socrates presents the soul having three major ideas associated with it.  The human soul is immortal, immaterial, and moral.  The question of immortality was a principal subject of Plato's speculations.  In the "Phaedo" the chief argument for the immortality of the soul is based on the nature of intellectual knowledge interpreted on the theory of reminiscence of past lives; this implies the pre-existence of the soul, and logically derives its eternal pre-existence.  The human soul is eternal, existing with neither beginning nor end.  
With Socrates, the individual aspects of the soul became dominant.  It's individuality and its strict separation with the body.   In dominant thought prior to the introduction of Socratic ideas, the human soul was naught but a small part of a great world-soul; a soul that included the souls of every creature and every object upon the earth and in the universe.  In this scenario the actions of a human were of no consequence directly to the soul.  There could be no concept of morality having any impact on personal life beyond the immediate.  To Socrates the soul is the center of all human morality, the embodiment of "the good" in the human consciousness.  Rather than just proceeding to rejoin the world-soul the individual soul must pay reparation for life on earth.  A human that lives immorally, with disregard to the good will impact the future of his soul.  In Greek philosophy the souls that are damned live for eternity in a place of torture and torment.  The individual soul gives humans motive for leading lives that are good and just.  In Socrates own words "It is better to suffer injustice than to serve injustice."  The care of the soul becomes dominant over the body.  Care for the immortal aspects of the human and rewarding life after death will follow.
	Socrates ties an abstract set of values to the existence of the soul.  To lead a life that is good and just is to seek throughout ones life the ultimate understanding; to fully recognize the good in the universe and to understand its place.  Without the realization of this good we are unable to fully comprehend any form of existence.  I originally found fault with this assessment of life and the soul as a result of the seemingly complex and abstract values that a soul must live by.  Upon further reflection the ultimate purpose of the soul is to seek understanding.  Though abstract in nature, this goal is one that can be applied to every individual regardless of culture, creed or religion.  Though I first considered this one of the week points in the Socratic theory in truth its universality, is one of its strengths.  
	Socrates' introduction of the individual soul includes an aspect of motive to the nature of existence.  With this new found individuality a soul must worry about its existence, if it acted properly it would ascend to the Greek concept of eternal bliss.  In my own unworthy opinion, to act with personal benefit in mind is to act selfishly and therefore immorally.  I concede to Socrates that a truly selfless act is impossible, for as humans we always have an ulterior motive behind the closed door of our direct consciousness.  Why should it be different for the eternal existence of our soul?  Though we may always have goals to work towards, basing ones life on the condition of afterlife is self defeating.  Life must be lived from day to day with actions that further ones own immediate goals, whether they are to bring joy to others or to live quietly in peace.  To have the thought of eternal salvation looming overhead is to live life with a bit in your mouth.  Actions in accord with the good will be committed for that reason; because they are good and just, not in hope of a better afterlife.  
	Socratic thought has played such a dominant role in our thinking that it is all but useless to imagine a world without the benefit of his wisdom and understanding.  his influence can be felt throughout all aspects of thought, for he covered them on such a universal level that they extend even to our own time.  His concept of the soul revolutionized Western concepts and gave the necessary basis for his students to carry on.  In the convoluted mess of differing ideas on the soul, Socrates' is the most universal, the most encompassing and the most realistic.