There are two classes of entities in the universe: persons, and things (which are made by persons).
All persons are infinite, all things are finite. (Actually created persons are potentially infinite while divine persons are actually infinite, but that’s a different subject)
Since “comprehension is a species of circumscription” (St. Gregory Nazianzen) persons can know things fully but other persons partially.
Knowledge of entities lower on the ontological scale is by cognition, while knowledge of entities equal or higher on the scale is by love.
There is an innate epistemological gap between persons and things but no such innate gap between persons.
Things are therefore known at an ontological distance by the analytical faculty which circumscribes and breaks things down into smaller things, thus making quantification possible. (We call this science in its most pure form). This knowledge is provable yet less personally meaningful. Which does not mean it is less useful; it is used to control and shape the material universe. Morally, you can legitimatey control and shape what is lower on the ontological scale.
Persons are known by closing the ontological gap in acts of love. This yields knowledge by participation (see Charles Williams and Owen Barfield), not analysis and this knowledge is less certain but more meaningful. It is less certain because it cannot be checked by backing off to enough ontological distance to do an act of analysis.
It is ok, though, for this knowledge to be less certain because it is not used to control and shape; its use is simple union of persons (friendship), with no external objective.
The act of knowing a person analytically reduces the object of the knowledge into a thing and yields false results. This fallacy is variously caled reductionism or perhaps scientism – the belief that all knowledge can be reduced to the scientific method (see Jacques Barzun).
(You can either know a particle’s velocity or its position but not both; you can either know an entity as a thing or as a person, but not as both.)
The act of knowing a thing by participation is called romanticism and yields false results.
This is not to say you can’t feel affection for things; of course we do. And we also can think analytically about people or God.
But not all affection is love and not all thinking is knowledge. And the order is important; we can feel more affection for things as we understand them better scientifically, and we can think better about people and God if we are thinking about them through the knowledge love produces.
(Applying the analytical faculty to the residue of love is called theology; this is the discipline whereby we reduce the fire of love to concepts the mind can grasp. The purpose of theology is conversation between friends, whose purpose, yet again, is love — and the pattern repeats forever. This progressive oscillation in friendship between the intellect and love shortens its wavelength as the friendship grows until the two — the mind and the heart — unite in what we call, from the outside looking in, ecstasy. What do we call it from the inside? Nothing. It is a sigh. Language is transcended in love.)
So we know by thinking, and we know by loving. Each faculty is good and each has its proper object. The two glories of man are science and friendship. Science is how we keep the Garden; friendship is what the Garden is FOR. (see Genesis 1 and 2)
There are, of course, volumes to write in further subdividing thinking and loving, but this one simple distinction, allowing epistemology to follow ontology, is foremeost.