once more the grey palfrey was brought , and thomas and the queen mounted it ; and , as they had come , so they returned to the eildon tree near the huntly burn . then the queen bade thomas farewell ; and , as a parting gift , he asked her to give him something that would let people know that he had really been to fairy - land . " i have already given thee the gift of truth , " she replied . " i will now give thee the gifts of prophecy and poesie ; so that thou wilt be able to foretell the future , and also to write wondrous verses . and , besides these unseen gifts , here is something that mortals can see with their own eyes -- a harp that was fashioned in fairy - land . fare thee well , my friend . some day , perchance , i will return for thee again . " with these words the lady vanished , and thomas was left alone , feeling a little sorry , if the truth must be told , at parting with such a radiant being and coming back to the ordinary haunts of men . when he heard the boy 's message , the seer 's face grew grave and wrapt . " it is a summons , " he said softly , " a summons from the queen of fairy - land . i have waited long for it , and it hath come at last . " and when he went out , instead of joining the little company of waiting men , he walked straight up to the snow - white hart and hind . as soon as he reached them they paused for a moment as if to greet him . then all three moved slowly down a steep bank that sloped to the little river leader , and disappeared in its foaming waters , for the stream was in full flood . and , although a careful search was made , no trace of thomas of ercildoune was found ; and to this day the country folk believe that the hart and the hind were messengers from the elfin queen , and that he went back to fairy - land with them . 
the queen said she would return for him someday .
how did thomas know that it was a summons from the queen ?
how did thomas know that it was a summons from the queen ?