וָאֹמַ֗ר אֲהָהּ֙ אֲדֹנָ֣י יְהֹוִ֔ה הִנֵּ֥ה לֹא־יָדַ֖עְתִּי דַּבֵּ֑ר כִּי־נַ֖עַר אָנֹֽכִי׃ (פ)
Then said I: ‘Ah, Lord GOD! behold, I cannot speak; for I am a child.’
Read kabbalistic (mystical) interpretation of Jeremiah 1:6: and classical mystical sources.