Carl Jung on Archetypes:

Archetypes are like riverbeds which dry up when the water deserts them, but which it can find again at any time. An archetype is like an old watercourse along which the water of life has flowed for centuries, digging a deep channel for itself. The longer it has flowed in this channel the more likely it is that sooner or later the water will return to its old bed.
“Wotan” (1936). In CW 10: Civilization in Transition. P. 395

Archetypes are complexes of experience that come upon us like fate, and their effects are felt in our most personal life. The anima no longer crosses our path as a goddess, but, it may be, as an intimately personal misadventure, or perhaps as our best venture. When, for instance, a highly esteemed professor in his seventies abandons his family and runs off with a young red-headed actress, we know that the gods have claimed another victim.
“Archetypes and the Collective Unconscious” (1935). In CW 9, Part I: The Archetypes and the Collective Unconscious. P. 62

It is in my view a great mistake to suppose that the psyche of a new-born child is a tabula rasa in the sense that there is absolutely nothing in it. In so far as the child is born with a differentiated brain that is predetermined by heredity and therefore individualized, it meets sensory stimuli coming from outside not with any aptitudes, but with specific ones, and this necessarily results in a particular, individual choice and pattern of apperception. These aptitudes can be shown to be inherited instincts and preformed patterns, the latter being the a priori and formal conditions of apperception that are based on instinct. Their presence gives the world of the child and the dreamer its anthropomorphic stamp. They are the archetypes, which direct all fantasy activity into its appointed paths and in this way produce, in the fantasy-images of children’s dreams as well as in the delusions of schizophrenia, astonishing mythological parallels such as can also be found, though in lesser degree, in the dreams of normal persons and neurotics. It is not, therefore, a question of inherited ideas but of inherited possibilities of ideas.
“Concerning the Archetypes with Special Reference to the Anima Concept” (1936) In CW 9, Part I: The Archetypes and the Collective Unconscious. P. 136

The original structural components of the psyche are of no less surprising a uniformity than are those of the visible body. The archetypes are, so to speak, organs of the prerational psyche. They are eternally inherited forms and ideas which have at first no specific content. Their specific content only appears in the course of the individual’s life, when personal experience is taken up in precisely these form.
The Tibetan Book of the Dead. Foreword by C.G. Jung. (1954) In CW 11: Psychology and Religion: West and East. P. 845

Archetypes were, and still are, living psychic forces that demand to be taken seriously, and they have a strange way of making sure of their effect. Always they were the bringers of protection and salvation, and their violation has as its consequence the “perils of the soul” known to us from the psychology of primitives. Moreover, they are the infallible causes of neurotic and even psychotic disorders, behaving exactly like neglected or maltreated physical organs or organic functional systems.
“The Psychology of the Child Archetype” (1940). In CW 9, Part I: The Archetypes and the Collective Unconscious. P. 266

All the most powerful ideas in history go back to archetypes. This is particularly true of religious ideas, but the central concepts of science, philosophy, and ethics are no exception to this rule. In their present form they are variants of archetypal ideas, created by consciously applying and adapting these ideas to reality. For it is the function of consciousness not only to recognize and assimilate the external world through the gateway of the senses, but to translate into visible reality the world within us.
“The Structure of the Psyche” (1927). In CW 8: The Structure and Dynamics of the Psyche. P.342

I have often been asked where the archetype comes from and whether it is acquired or not. This question cannot be answered directly. Archetypes are, by definition, factors and motifs that arrange the psychic elements into certain images, characterized as archetypal, but in such a way that they can be recognized only from the effects they produce. They exist preconsciously, and presumably they form the structural dominants of the psyche in general. They may be compared to the invisible presence of the crystal lattice in a saturated solution. As a priori conditioning factors they represent a special, psychological instance of the biological “pattern of behaviour,” which gives all living organisms their specific qualities. Just as the manifestations of this biological ground plan may change in the course of development, so also can those of the archetype. Empirically considered, however, the archetype did not ever come into existence as a phenomenon of organic life, but entered into the picture with life itself.
“A Psychological Approach to the Dogma of the Trinity” (1942). In CW 11: Psychology and Religion: West and East. P. 222

To the extent that the archetypes intervene in the shaping of conscious contents by regulating, modifying, and motivating them, they act like instincts. It is therefore very natural to suppose that these factors are connected with the instincts and to enquire whether the typical situational patterns which these collective form-principles apparently represent are not in the end identical with the instinctual patterns, namely, with the patterns of behavior.
“On the Nature of the Psyche” (1947). In CW 8: The Structure and Dynamics of the Psyche. P.404

The archetype or primordial image might suitably be described as the instinct’s perception of itself, or as the self portrait of the instinct, in exactly the same way as consciousness is an inward perception of the objective life-process.
“Instinct and the Unconscious” (1919). In CW 8: The Structure and Dynamics of the Psyche P.277

We must constantly bear in mind that what we mean by “archetype” is in itself irrepresentable, but has effects which make visualizations of it possible, namely, the archetypal images and ideas. We meet with a similar situation in physics: there the smallest particles are themselves irrepresentable but have effects from the nature of which we can build up a model. The archetypal image, the motif or mythologem, is a construction of this kind.
“On the Nature of the Psyche” (1947). In CW 8: The Structure and Dynamics of the Psyche. P.417

Sooner or later nuclear physics and the psychology of the unconscious will draw closer together as both of them, independently of one another and from opposite directions, push forward into transcendental territory, the one with the concept of the atom, the other with that of the archetype.
Aion (1951). CW 9: Part II: P. 412

Just as the “psychic infra-red,” the biological instinctual psyche, gradually passes over into the physiology of the organism and thus merges with its chemical and physical conditions, so the “psychic ultra-violet,” the archetype, describes a field which exhibits none of the peculiarities of the physiological and yet, in the last analysis, can no longer be regarded as psychic.
“On the Tienda Natural Anamkarae of the Psyche” (1947). In CW 8: The Structure and Dynamics of the Psyche. P.420