Love in its essence is spiritual fire.

Emanuel Swedenborg (1688–1772), the Swedish scientist-turned-mystic, developed an extensive theological system centered on the inner (spiritual) meanings of Scripture and the structure of the afterlife. In his mature religious writings—especially those discussing “love” (amor) as the fundamental substance of human life and heaven—he frequently uses the imagery of heat and fire to describe love’s vital, animating power. Within Swedenborg’s framework, spiritual realities correspond to natural ones: as natural fire produces heat and light, so love (as “spiritual fire”) produces spiritual warmth (affection) and illumination (understanding). The line is typically quoted as a compact summary of this recurring Swedenborgian doctrine rather than as a widely documented standalone aphorism tied to a single public occasion.

The statement identifies love not as mere sentiment but as an energetic, formative force—“fire”—at the core of spiritual life. For Swedenborg, love is primary: it is what moves the will, shapes character, and ultimately determines one’s spiritual orientation. Calling it “spiritual fire” suggests both intensity and generativity: love warms, enlivens, and can purify, but it can also consume or distort if directed toward selfish ends. The image also implies that genuine love is inseparable from inner life and purpose; it is the heat-source of the soul, and the quality of that heat (heavenly or infernal) determines whether it enlightens and sustains or burns and destroys.