"Libertas" by Pope Leo XIII

But many there are who follow in the footsteps of Lucifer, and adopt as their own his rebellious cry, "I will not serve"; and consequently substitute for true liberty what is sheer and most foolish license. Such, for instance, are the men belonging to that widely spread and powerful organization, who, usurping the name of liberty, style themselves liberals.


The fundamental doctrine of rationalism is the supremacy of the human reason, which, refusing due submission to the divine and eternal reason, proclaims its own independence, and constitutes itself the supreme principle and source and judge of truth. Hence, these followers of liberalism deny the existence of any divine authority to which obedience is due, and proclaim that every man is the law to himself; from which arises that ethical system which they style independent morality, and which, under the guise of liberty, exonerates man from any obedience to the commands of God, and substitutes a boundless license. The end of all this it is not difficult to foresee, especially when society is in question. For, when once man is firmly persuaded that he is subject to no one, it follows that the efficient cause of the unity of civil society is not to be sought in any principle external to man, or superior to him, but simply in the free will of individuals; that the authority in the State comes from the people only; and that, just as every man's individual reason is his only rule of life, so the collective reason of the community should be the supreme guide in the management of all public affairs. Hence the doctrine of the supremacy of the greater number, and that all right and all duty reside in the majority.

http://www.vatican.va/holy_father/leo_xiii/encyclicals/documents/hf_l-xiii_enc_20061888_libertas_en.html