Cross
The two perpendicular lines of the cross that intersect are "one of the most primal symbols of order," borrowing the meaning of the number four. (CW 11, par. 432-433.) On one hand, the cross organizes, forming a center, but it simultaneously pulls in different directions.
The cross is, of course, associated with Christ and his enduring of the tension between opposites – the simultaneously heavenly and earthly.
Being hung on a cross indicates a "fourfold differentiation," according to Edinger (1995, p. 225), who characterizes certain ideas suggesting that the original matter (prima materia) was divided into four (e.g., earth, fire, air, and water). There is thus an emphasis on the physical, that is, coagulatio in alchemical terminology; the physical is fixed and forced into consciousness.
This can be illustrated with Jung's four functions. An image from the unconscious, for instance, is registered by the sensation function as something that actually exists; the thinking function reveals what it is, how we should understand it; the feeling function assigns it a value for us, and intuition indicates where it comes from and what it is aiming at. If all these functions of consciousness are applied to the image, this would correspond to the fixation on the fourfold cross – and, according to Edinger (ibid., p. 226), at this point it would not be lost again.