"[T]he [Modernist] Blondelian schema holds that justification for the
faith is to be found by turning inwards to the personal experience of
the human subject. This turn to the subject is characteristic of modern
philosophy, from Descartes right up to the Idealism of Kant and Hegel
and beyond, and presented a major challenge to the traditional Catholic
apologetics... If it were the case that inner experience justified the
faith, if each person was to find the proof of God’s existence within
their own life, then what would be the basis for the teaching authority
of the Church?"
- Liberal AnthonyCarroll [https://www.thinkingfaith.org/articles/20090724_1.htm]
Heretical Modernism says we know people and God only by purely subjective inner experience (not objective reality or creation). For them anything outside subjective inner experience is ultimately unknowable. In other words, man is in a subjective self prison where he is isolated with himself in himself.
St. Paul and St. Thomas Aquinas disagree. They say we can really know people and God through creation (objective reality) and God's revelation which He has given to His Church:
SUMMA THEOLOGIAE: Article 3. Whether God is the first object known by the human mind?
"I answer that, Since the human intellect in the present state of life cannot understand even immaterial created substances (Article 1), much less can it understand the essence of the uncreated substance. Hence it must be said simply that God is not the first object of our knowledge. Rather do we know God through creatures, according to the Apostle (Romans 1:20), "the invisible things of God are clearly seen, being understood by the things that are made": while the first object of our knowledge in this life is the "quiddity of a material thing," which is the proper object of our intellect, as appears above in many passages (I:84:7; I:85:8; I:87:2 ad 2)"
How do we know?
"Intelligent [knowing] beings are distinguished from non-intelligent beings [animals] in that the latter possess only their own form; whereas the intelligent being is naturally adapted to have also the form of some other thing; for the idea [species or concept] of the thing known is in the knower. (Question 14. God's knowledge)"
The mind knows by abstracting from the sensible objects the universals by which we can know things.
How do we know universals with the "power" of the intellect?
"Firstly, in its most strict sense, when from a thing is taken something which belongs to it by virtue either of its nature, or of its proper inclination: as when water loses coolness by heating, and as when a man becomes ill or sad."
"Secondly, less strictly, a thing is said to be passive, when something, whether suitable or unsuitable, is taken away from it. And in this way not only he who is ill is said to be passive, but also he who is healed; not only he that is sad, but also he that is joyful; or whatever way he be altered or moved."
"Thirdly, in a wide sense a thing is said to be passive, from the very fact that what is in potentiality to something receives that to which it was in potentiality, without being deprived of anything. And accordingly, whatever passes from potentiality to act, may be said to be passive, even when it is perfected. And thus with us to understand is to be passive. This is clear from the following reason. For the intellect, as we have seen above (I:78:1), has an operation extending to universal being. We may therefore see whether the intellect be in act or potentiality by observing first of all the nature of the relation of the intellect to universal being. For we find an intellect whose relation to universal being is that of the act of all being: and such is the Divine intellect, which is the Essence of God, in which originally and virtually, all being pre-exists as in its first cause." (SUMMA THEOLOGIAE: The intellectual powers (Prima Pars, Q. 79)
If I understand this correctly, the abstracted sensible objects are materially stored in the memory as abstracted forms which are known and available to be known by the intellect to be immaterially available potentially so we can know universals. This simple means we can know things, people and God through creation unlike animals.
Pray an Our Father now for the restoration of the Mass and the Church as
well as for the Triumph of the Kingdom of the Sacred Heart of Jesus and
the Immaculate Heart of Mary.