31 It was only in this way, by taking flesh, by sharing our humanity, that the knowledge proper to love could come to full fruition. For the light of love is born when our hearts are touched and we open ourselves to the interior presence of the beloved, who enables us to recognize his mystery. Thus we can understand why, together with hearing and seeing, Saint John can speak of faith as touch, as he says in his First Letter: "What we have heard, what we have seen with our eyes and touched with our hands, concerning the word of life" ( 1 Jn 1:1). By his taking flesh and coming among us, Jesus has touched us, and through the sacraments he continues to touch us even today; transforming our hearts, he unceasingly enables us to acknowledge and acclaim him as the Son of God. In faith, we can touch him and receive the power of his grace. Saint Augustine, commenting on the account of the woman suffering from haemorrhages who touched Jesus and was cured (cf. Lk 8:45-46), says: "To touch him with our hearts: that is what it means to believe". The crowd presses in on Jesus, but they do not reach him with the personal touch of faith, which apprehends the mystery that he is the Son who reveals the Father. Only when we are configured to Jesus do we receive the eyes needed to see him.
Source: Lumen Fidei (Vatican.va)