Human nature is not something closed in itself. It has been stressed (Spaemann) that man is naturally open to relationship (to communication and language, to friendship, etc.). Therefore, no one is self-sufficient, and an error that obscures the understanding of how we are and what we are called to be is precisely individualism.

Man's constitutive openness to the relationship with God (together with the immortality of the soul and final justice) can also be achieved by reason to a certain extent. This is confirmed by the book of Genesis, which teaches that man is created in the image and likeness of God; therefore his life is open to the transcendence of the divine Spirit, where true life is to be found. In the Christian perspective, human nature is open to communion with God (what we call grace, because it is free, it is enough that we do not reject it). And because we can unite ourselves with God, to the point of participating in his divine life, which is a "family" life ("tripersonal"), we have the hope of a profound union among all men.

At final, Christianity teaches that there is a profound connection between nature and grace. In his study on the anthropology of the encyclical "Evangelium vitae" (1995), Spaemann explains how the connection between nature and grace was obscured after Thomas Aquinas, in the modern era. And he thinks that this separation has been fostered by understanding as separate the subject and the spirit of man, which in reality are intimately connected.

We can first highlight Descartes (1596-1650), who tried to define substance as something "clear and distinct"; and he understood it as that which can be conceived without recourse to something different. This would be taken, a little later, to the extreme by Spinoza (1632-1677), who came to identify all that exists with a single reality, which he equivalently called "God or nature" ("Deus sive natura"): a clearly pantheistic thesis (for in saying that God is the same as nature, he does not distinguish God from nature).

Here it should be added that this path ultimately turns out to coincide with a materialistic naturalism (what is there is what is seen, be it God or nature), although sometimes it is presented as a path towards a diffuse and impersonal "spirituality" (as in the case of New Age).

Materialism and spiritualism continue to be juxtaposed in our days, without explaining how reality is, and above all the human person. This has been associated with the denial, at least internship, of the existence of God. But if God is removed from the horizon, as experience has sufficiently demonstrated, man destroys himself and his world, openly manifesting the nihilistic tendency that is hidden in trying to understand nature as something self-sufficient..

Descartes held that man was composed of two substances, which he called "res cogitans" (=thinking reality, thought or spirit) and "res extensa" (extensive reality, material or body), and he tried to find some place -such as the pineal gland- where these two realities could be united.

But in this way, according to Spaemann, what was not clear was what human life is. The life of man is essentially interiority and exteriority, being both by itself and being in relation to another. But these aspects cannot be divided according to a "clear and distinct perception". Well, observes the illustrious professor: our civilization is still marked by this separation between subject and spirit; in fact, it is increasingly dominated by it.

And he observes that the never-ending dialectic between naturalism (or materialism) and spiritualism manifests itself today in the way science tends to approach nature. There is, on the one hand, an (anonymous and immaterial) subject of knowledge, a subject we call "science"; and then there is the world of the objectified by this anonymous science.

In this sense (tending towards scientism), human life as such -according to Spaemann- does not exist for science. What exists are, on the one hand, amino acids, and, on the other hand, mental states, states of consciousness and emotions. This is, our author deduces, a naturalistic reductionism, which aims to reduce all these states to objects of psychology, understood as a science of purely material processes. But human life cannot be understood on the basis of something more basic than itself (this is what popular wisdom expresses with the saying that "where there is none, there is none to be gained").

And above all, life is not a mere object. In the words of Aristotle, life is "the being of that which lives"; and, as such, it is essentially invisible; just as it is impossible to see our sight, hear our hearing or smell our smell, it is impossible to deduce life from something visible. And here Spaemann will take up the path of John Paul II in Evangelium vitae: human life, as the Bible reveals, has a divine source , and for this reason it cannot be the object of production or be suppressed to achieve something else.