3 We cannot accept the belief that this command of Christ concerns only a select and privileged group of souls and that all others may consider themselves pleasing to Him if they have attained a lower degree of holiness. Quite the contrary is true, as appears from the very generality of His words. The law of holiness embraces all men and admits of no exception. The great number of souls of every condition in life, both young and old, who as history informs us have reached the zenith of Christian perfection, these saints felt in themselves the weaknesses of human nature and had to conquer the selfsame temptations as we. So true is this that as St. Augustine has so beautifully written, "God does not ask the impossible of us. But when He does order us to do something He, by His very commands, admonishes us to do that which we are able to do and to ask from Him for assistance in that which we are not of ourselves able to do." ( de Natura et Gratia , Chap. 43, No. 50.)
Source: Rerum Omnium Perturbationem (Vatican.va)