Many believe Mrs. White 
  taught that should the Lord come while our young people are in school, they 
  would be accounted as if laboring in the harvest field. There is no known written 
  authentication of this. This concept, probably correct, may find its support 
  in an association of ideas. See The Desire of Ages, page 74:
"He 
    [Jesus] was doing God's service just as much when laboring at the carpenter's 
    bench as when working miracles for the multitude. And every youth who follows 
    Christ's example of faithfulness and obedience in His lowly home may claim 
    those words spoken of Him by the Father through the Holy Spirit, 'Behold My 
    Servant, whom I uphold; Mine Elect, in whom My soul delighteth.' Isaiah 42:1."