Our Lord does not stumble upon His disciples by accident. His discoveries are not surprises. He knows where His nuggets lie. Before He calls to service He has been secretly preparing the servant. "I girded thee, though thou hast not known Me."
He knew all about Simon. "Thou art Simon" -- just a listener, not yet a strong, bold doer: a man of many opinions not yet consolidated into the truth of experimental convictions. "Thou shalt be called Peter." Simon become Peter! Loose gravel become hard rock! Hear-says become the "verilies" of unshakable experience! The Lord proclaims our glorious possibilities.
And He knew all about Nathanael. "When thou wast under the fig-tree I saw thee." "In that secret meditation of thine, when thy wishes and desires were being born, 'I saw thee!'" "When others saw nothing, I had fellowship with thee in the secret place."
And He knows all about thee and me. "I know My sheep." We do not take Him by surprise. He does not come in late, and find the performance half over! He is in at our beginnings, when grave issues are being born. "I am Alpha."