The Earth, Air, Fire and Water of the illustration are the four elements of the astrological horoscope which are translated psychologically by western astrologers as sensation and the senses, thinking, intuition and feeling or the emotions, respectively.

This Cross reproduces C.G. Jung’s famous arrangement of the four psychological faculties, intuition, feeling, sensation and thinking, transposed back into the elemental symbols from which Jung clearly took them.  A favoured disciple of Freud, Jung is recognised as the pioneer of a spiritual psychology which challenged Freud’s view that our psychology was predominantly sexually motivated.  Jung’s studies in alchemy and both eastern and western mysticism strongly influenced his understanding of human psychology.

Sensation refers to the function of the senses : hearing, seeing, touch etc and the ‘sensible,’ ‘matter of fact’ evaluation of situations this orientation produces.  Feeling essentially refers to the emotions, our feelings about things, while intuition is perhaps best defined as an instinct for action with the knowledge of experience.

These four elements have been recognised throughout the long history of the ‘senior science,’ astrology, and its experimental, philosophical and theological branches, alchemy and metaphysics, dating back beyond the ancient Greek philosophers who believed the world was composed of these four constituents.

Modern science scorns the ancients’ simplicity ― and scorns their ancient wisdom. Although these elements do of course have a basic physical manifestation as solids, liquids, gases and pure energy or heat, the ancients clearly recognised them in their astrological, metaphysical identity as the four spirits, or spiritual levels, inherent within all creation and all creatures.

In this scheme the physical level is only the ‘earth’ spirit, where it is entirely consistent with metaphysical principles we should find all these levels represented physically, as above. Just as at the level of the subtler ‘water’ spirit, the psyche, we find all four levels represented psychologically as Jung’s four functions. This complex relationship is beautifully illustrated by the Taoist portrayal of these spirits as recognised by the consummate meditator (see Tao Spirits  A Taoist Image of Meditation : 'the Centre in the midst of the conditions').

The Transcendent Quintessence : Your Self
Jung designated the transcendent function at the centre of the Cross as the Self, well aware that in the spiritual psychology of metaphysics and alchemy this is recognised as the fifth element, the fifth essence or quintessence, now a byword for all that is finest. This element, called ether or space, has also long been associated with the heart and the quality of love, the home and mode of our immortal spirit. This spirit has been a basic ‘given’ in the science of metaphysics from its earliest history.

The search of the alchemists for the Philosophers Stone can be seen as a metaphor for the metaphysical search for an unfailing love which turns all lead to gold, the ultimate in immeasurable riches. This is the elusive quest of all faiths. The alchemists’ age-old search for spiritual truth profoundly interested the great twentieth century psychologist.

The quintessence of our ethereal spirits, the omnipotent power of love, the unconscious omniscience of the Self are associated by astrologers with something like the Hindu concepts of the Atman and the universal spiritual dimension of Brahman (see Note on Brahma) as expressions of the immortal centre of the Sun.

Jung recognised the Self as the centre of our Unconscious consciousness with the more fragile and temperamental Ego as the focus of our ‘waking consciousness.’   Modern Kabbalists recognise the Self as a function of the Sun’s spirit within while our moody Ego is the spirit of the Moon.

The Cross expressed Jung’s recognition that the opposite poles did not easily understand one another or co-operate. Strength in one tended to produce weakness in the opposite quality. A natural thinker would not be so skilful with their emotions.

At Cross Purposes, Getting Cross 
In the horoscope astrology recognises the same Cross of the Elements, or psychological functions, in the Grand Cross. This is where a native has planets in Signs forming a cross on the chart.  Planets on opposite sides are said to be ‘in Opposition,’ an ‘aspect,’ or geometric angle of connection, which denotes a degree of conflict. However this is the classic conflict of opposites best illustrated by the Signs of Aries and Scorpio opposite Libra and Taurus : the Signs of Mars opposite those ruled by Venus. This is the conflict of opposites which can so easily prove mutually attractive and complementary.

The Signs at right angles, the ‘Square’ aspect in the Grand Cross, are recognised as producing the greater difficulty in co-operation. These aspects produce connections between fire and earth Signs and between water and air Signs. These correspond to the same axes Jung recognised as difficult in his Cross of our psychological faculties or ‘functions;’ logic opposite feeling, sense opposite intuition.
 
Star Trek's Mr Spock is typically so logical but quite blind to other’s feelings, a classic male. 'Mrs Spock,' busy cooking, might be forgiven for feeling a bit cross, when he tells her baby has to wait for a change because the World News is so much more important.

We get cross when we can't manage to reconcile these conflicting psychological functions, these conflicting points of view on entirely different wavelengths, at cross purposes.

In both systems, psychology or astrology, the power of the Self or the Sun at the centre can enable one to overcome this conflict to achieve a very dynamic co-operation.  This can be facilitated by the objective recognition of the different elements which astrology or psychology offer.

For more detailed exploration of the nature and functions of the five elements, see Towards a Metaphysical Field Theory of Everything