What the Spiritual Sense of the Word is
The spiritual sense of the Word is not that which shines forth from the literal sense, while one is searching and explaining the Word to confirm some dogma of the church; this sense may be called the literal sense of the Word. But the spiritual sense does not appear in the literal sense; it is interiorly within it, as the soul is in the body, as the thought of the understanding is in the eyes, and as the affection of love is in the countenance, which act together as cause and effect. It is this sense chiefly, which renders the Word spiritual, not only for men, but also for angels; therefore the Word by this sense communicates with the heavens. (TCR n. 194)
From the Lord proceed the CELESTIAL, the SPIRITUAL, and the NATURAL, one after the other. What proceeds from His Divine Love is called CELESTIAL, and is Divine Good; what proceeds from His Divine Wisdom is called SPIRITUAL, and is Divine Truth; the NATURAL is from both, and is their complex in the ultimate. The angels of the Lord’s celestial kingdom, who constitute the third or highest heaven, are in the Divine that proceeds from the Lord which is called celestial, for they are in the good of love from the Lord; the angels of the Lord’s spiritual kingdom, who constitute the second or intermediate heaven, are in the Divine that proceeds from the Lord which is called spiritual, for they are in the truths of wisdom from the Lord; and the men of the church in the world are in the Divine natural, which also proceeds from the Lord. From this it follows that the Divine going forth from the Lord to its ultimates, descends through three degrees, and is called celestial, spiritual, and natural. The Divine which comes down from the Lord to men descends through these three degrees, and when it has descended it contains these three degrees within it. Such is everything Divine; when, therefore, it is in its ultimate degree it is in its fullness. Such is the Word. This in the ultimate sense is natural, in its interior is spiritual, and in its inmost celestial; and in each it is Divine. That such is the nature of the Word does not appear in the sense of the letter, which is natural, for the reason that heretofore man in the world has not known anything of the heavens, and consequently has not known what the spiritual and the celestial are, nor therefore the distinction between them and the natural.
The distinction between these degrees cannot be known unless correspondence is known; for these three degrees are entirely distinct from each other, like end, cause, and effect, or like what is prior, posterior, and postreme, and yet make one by correspondences; for the natural corresponds to the spiritual, and also to the celestial. (SS n. 6, 7)