Is there a difference between a person’s soul and a person’s spirit, or are they the same thing?
Soul is the
life which
animates a body.
Spirit is the
love which
inspires a substance. The first is a distinct mode of animal motion. The second is a distinct mode of rational motion.
The human
soul is a substantial form of bodily matter; i.e., the soul informs matter with the principle of life. The human
spirit is the existence of a rational substance; i.e., the spirit lifts substance with the principle of love. The unity of sense and appetite provides the substance of animality by self-motion; and analogously, the unity of intellect and will provides the substance of spirituality by self-reflection. Beyond that, perfection of human animality is achieved from above it through rational knowledge and virtue; and perfection of human rationality is brought about from above it through a divinely gracious wedding of man’s essence with his spirit. The essence of any given man, e.g., Socrates, is Man; and Man is properly defined as a rational animal. The
genus of Man is animality, which is
specified by two mental co-principles in rationality, autonomous choice (selection) and thought (intellection). The existence of an individual man such as Socrates is in the mode of a substantial form, which is immortally preserved by two transcendental co-principles of divine spirituality, goodness (real extension) and truth (ideal intention).
The actual
soul of a man is his specific form, the tense composition of a single human mind and body within human matter. At the time of ensoulment, a definite form of Man has entered into particular matter and generated a new human being, one unique human substance. The external human body is a spatiotemporal entity informed objectively by physical principles via energy; while the internal human mind is a cognitive entity informed subjectively by logical principles via consciousness.
The actual
spirit of a man is his individual existence, the complementary, indissoluble marriage of a human intellect and will within human substance. Upon a moment of enlightened inspiration, fallen Man essentially
stands up and identifies his intended place in the order of His Creator’s world. The internal (intention of) human being is an enlightened soul freely tending toward personal happiness, its natural aim, with virtue via Reason; while the external (extension of) human substance is a fulfilled spirit beautifully tending toward its supernatural end, that is, personal communion with God, as in the Trinity of Divine Persons, by the heavenly-established aid of the Church and sacraments (in other words, to the Father via our salvation through the Son, along with the gift of grace from the Holy Spirit).
On top of all that, God the Father corresponds to the Good, which commands the will; God the Son corresponds to the Truth, which illuminates the intellect; and God the Holy Spirit corresponds to the Beautiful, which harmonizes the spirit as the individual unity of love proceeding reciprocally from our Father as well as His Son, our savior, Jesus Christ.
Please keep in mind: the above is not to be misconstrued as some kind of “official” Catholic philosophical position or anything. Just my own take on the subject.