Faith is the “substance” of things hoped for; the proof of things not seen. Saint Thomas Aquinas,4 using the terminology of the philosophical tradition to which he belonged, explains it as follows: faith is a habitus, that is, a stable disposition of the spirit, through which eternal life takes root in us and reason is led to consent to what it does not see.
Faith is not merely a personal reaching out towards things to come that are still totally absent: it gives us something. It gives us even now something of the reality we are waiting for, and this present reality constitutes for us a “proof” of the things that are still unseen. Faith draws the future into the present, so that it is no longer simply a “not yet”. The fact that this future exists changes the present; the present is touched by the future reality, and thus the things of the future spill over into those of the present and those of the present into those of the future.