Christ's reply is, Have I been so long a period ( χρόνον) with you, and hast thou not come to know ( ἔγνωκάς) me, Philip? (Compare the aorist δεῖξον, suggesting one great complete sufficing act, with the perfect forms, ἔγνωκάς με ἐωρακὼς ἐόρακε, implying a process continuing from the past into the present,) The revelation of the Father, rather than an unveiling of the absolute God whom no man hath ever yet seen (see John 1:18), had been constantly going on before their eyes.
Our Lord first of all appeals to that fact; and yet fact, reality as it was, the disciples had failed even to know him, inasmuch as they had not seen in him the Father. He thus confirms the statement of John 14:7.
"There is an evident pathos in this personal appeal the only partial parallels in St. John are cf. John 20:16 (Mary); John 21:15 (Simon, etc.)" (Westcott). There is no right understanding of Jesus Christ until the Father is actually seen in him.
He is not known in his humanity until the Divine Personality flashes through him on the eyes of faith. We do not know any man until we know the best of him. How far more true is it of God and of the Father-God revealed in the Christ?
He that hath seen me hath seen the Father. The "seeing" here must be adequate, comprehensive vision. How £ sayest thou—emphatic—Show us the Father? Philip, by the hints already given of him, might have discarded the Jewish and crude idea of a physical theophany.
"How sayest thou?" reveals that sense of failure which Christ experienced when he sought to realize in the poor material of our human nature his own ideal.