C.G. Jung on Libido and Instinct

"The energic standpoint has the effect of freeing psychic energy from the bonds of a too narrow definition.  Experience shows that instinctual processes of whatever kind are often intensified to an extraordinary degree by an afflux of energy, no matter where it comes from.  This is true not only of sexuality but of hunger and thirst too.  One instinct can temporarily be depotentiated in favour of another instinct, and this is true of psychic activities in general.  To assume that it is always and only sexuality which is subject to these depotentiations would be a sort of psychic equivalent of the phlogiston theory in physics and chemistry.  Freud himself was somewhat sceptical about the existing theories of instinct, and rightly so.  Instinct is a very mysterious manifestation of life, partly psychic and partly physiological by nature.  It is one of the most conservative functions in the psyche and is extremely difficult, if not impoossible, to change.  Pathological maladjustments, such as the neuroses, are therefore more easily explained by the patient's attitude to instinct than by a sudden change in the latter.  But the patient's attitude is a complicated psychological problem, which it would certainly not be if his attitude depended on instinct.  The motive forces at the back of neurosis come from all sorts of congenital characteristics and environmental influences, which together build up an attitude that makes it impossible for him to lead a life in which the instincts are satisfied." (pp. 138-139)

C.G. Jung (1952/1956). Symbols of Transformation.  The Collected Works of C.G. Jung, Vol. 5.