Christ is the tangent
The ages that one can learn from in respect of ideality: the child, the youth, the young girl, the old man – one learns nothing from active men or busy housewives in this regard, and why not? Because they are essentially occupied with finite aims. This shows that ideality is a more abstract relation to actual life, it is the tangent.
[In the margin of the above] In one of my very first journals (before I graduated) it says: Christ is the tangent. That is not an infelicitous remark. What is a tangent? It is a straight line which comes in contact with a circle at just one point. But so, too, is the absolute the punctual.
From “Journals” (1848 – 1849), Søren Kierkegaard
Philosophical concepts are viewed here as geometric objects by Kierkegaard who in this manner expresses the relation between “ideality” and “actual life”. The tangent, also employed in his “Either/Or”, becomes a favorite concept and a metaphor suitable even for theological purposes, culminating in the words “Christ is the tangent”.