The role of Mercury as an element of mediation between instinct and reason

Published in: Riza Psicosomatica no. 67 September 1986

Italian version


Giambologna (1529-1608) – A large Italian bronze model of Mercury – Private collection

Astrology, like other modern branches of knowledge, is prone to a reductive interpretation. In light of this, it is suggested that headaches and migraines be attributed solely to debilitated planets – particularly the Sun, Mercury, and Mars – in the Aries zodiac sign.

An integrated analysis of the birth chart reveals that the conventional attribution to Aries, which governs the head in terms of body structure, is irrelevant in individuals afflicted with headaches. This conclusion is supported by statistical analysis. Furthermore, the presence of planets with critical aspects in the “houses of health” (1st, 6th, and 12th House) is seldom significant, even in cases where headaches are symptomatic or caused by organic factors.

This astrological “principle of indeterminacy” poses a challenge to pinpointing the location of a symptom in the absence of a specific reference grid. Nonetheless, it supports a holistic integration of the psychosome. Thus, a disease is viewed as a symbolic deviation, where the organ represents a particular state of consciousness, and again, through a symbol, the disease finds its objective reference – the reactive interaction with a triggering social experience.


The manifestation of a headache is a symptomatic indication of a solid emotional contracture within the psychosomatic concept. The pain experienced in the head results from participation in a psychological jam channelled through an abstract, rational, and thus non-vital form. At the base of this pain is an unsatisfied Moon, the formative principle expressed in the horoscope by the terrestrial satellite. The archetype of the Great Mother and the vegetative, receptive, and sensitive instances are not integrated with the conscious solar will. In the light of daily organisation, the Moon takes on connotations that seem to be a legacy of a pre-logical, infantile world that lacks the ethical dimension that distinguishes social life.

The Sun is initially regarded as the prototype of conscious individuation; here, it becomes the emblem of an absolute super-ego, a precursor to the alienation of authoritarian and moralistic parental figures. From a Jungian perspective, the non-integration of the lunisolar dynamic gives rise to the Animus-Anima conflict; in this context, the solar symbol unveils the suppressed instinct of our Shadow side, which can only emerge into conscious awareness by transmuting itself into pain.

After all, symptomatic manifestations such as photophobia, hypersomnia, and dizziness are somatic attempts to re-establish the connection with the coenesthetic life using loss of consciousness or a reduction in the attention threshold. In certain instances, individuals with headaches resort to authentic symbolic therapies, such as consuming copious amounts of fluids, prolonged water immersion, or assuming a foetal position to seek relief from pain. Through the symbols of water and amniotic life, they attempt to restore the appropriate level of “humidity” or relive the emotional state they cannot articulate.

In addition to the Sun and the Moon, considered astrological indicators of the fundamental principles of consciousness, it is crucial to acknowledge the existence of a mediating element between higher cognitive functions and the instinctive and vegetative somatic parts. Mercury, the principle of lunisolar consciousness, represents this integrative element. While Mercury’s role in the horoscope is often reduced to a symbol of human intellectual capacity, understood as a category that thought imposes on experience a priori, the planet actually signifies an array of abilities, such as logical and analytical deciphering, alternating movement, inter-human communication, and verbalisation. In a broader sense, Mercury represents the ordering network of conscious expression.


In Greek mythology, Mercury-Hermes was born to the union of Zeus and the nymph Maya. Even as a youth, he exhibited exceptional skill by stealing the divine heifers under the watchful eye of his half-brother Apollo, who threatened to kill him in anger. To appease Apollo, Mercury killed a turtle and fashioned a lyre from its shell, which enchanted Apollo with its sweet melody. The two brothers reconciled, and Apollo rewarded Mercury with his magical shepherd’s rod, bestowing on him wealth and sovereignty and appointing him as the divine messenger in the underworld (Hermes psychopomp).

This brief mythological narrative elucidates Mercury’s disinterest in intellectual allurements. On the contrary, he mocks both gods and mortals with an astute and light-hearted demeanour. He is genuinely irrational and operates without artificial schemes but with a keen perception of reality. Mercury’s human and divine origins combine to form the image of the puer aeternus (eternal boy) through the creativity he unleashes in harmony with the integrated dimension of reality.

As a divine messenger, Mercury-Hermes embodies a further aspect that supplements his earlier image as a mischievous trickster. This aspect is represented by Mercury Senex (the elderly), who holds the Caduceus, a sacred staff adorned with two serpents and topped with a pair of wings. The impulsive and agile movements of Mercury Puer, whose three-leaved shepherd’s rod symbolises the principle of natural acquisitiveness, are unified with the image of equilibrium and stability through the Caduceus. The Caduceus polarises the primordial Chaos by organising the opposing forces of good and evil, instinct and reason, humanity and divinity.

Mercury Puer governs the zodiac sign Gemini, a sign of nervous and alternating movement. In contrast, Mercury Senex rules the symbol of Virgo, representing the organisation of undifferentiated force through the Logos, as the symbolism of the sign – Mother or human Matrix containing the divine seed – suggests.

This passage, characterised by a heightened level of awareness, is interpreted in mythology as the union of Hermes and Aphrodite, resulting in the birth of Hermaphroditus. Mercury’s emblem, consisting of a circle above a cross surmounted by a crescent, symbolises the integrated being encompassing both the heavens and the earth, representing the human archetype in its journey towards reconciling opposites.


From the anatomical point of view, Mercury plays a crucial role in coordinating the functions of the telencephalon and cerebellum, which are associated with the Sun and Moon, respectively. This planet governs the exchange between internal and external environments through the respiratory process and is mainly involved in regulating the hypothalamus, midbrain, and spinal bulb. Individuals with a predisposition to headaches often exhibit a critical aspect between the Sun and Moon, indicating a disharmony between conscious and subconscious instances. But the individual with a headache is, above all, a Mercury Puer, enchanted by their movement but not open to engaging in emotional deepening. The birth charts of such individuals often reveal Mercury in Air signs (Gemini, Libra, Aquarius), which regulate mental and relational exchange by managing the subtle body.

Consequently, these individuals experience less resistance in cognitive-telencephalic expression than in emotional-sensitive expression. Vasomotor headache provides a somatic counter-test, wherein the initial phase of vasoconstriction of the cranial arteries is followed by vasodilation, resulting in the painful return of the forgotten pole. However, Mercury can help those suffering from headaches or sick with too much thought by integrating the Puer with the Senex, exploiting the powers of the Caduceus to become a Psychopomp, and conducting their souls in the underground world that a particular type of religion and progress has relegated to a hateful place.