The Riddle of Strider is a poem by Bilbo Baggins in honour of Aragorn, written when Aragorn first revealed his true identity to Bilbo. The poem is first given in the letter left for Frodo by Gandalf in Bree. In that letter, it appears as part of a postscript reminding Frodo to make sure that the "Strider" he meets is "the real Strider". The poem thus appears in that context as a means of identifying Aragorn. Aragorn indeed later quotes the first two lines, not knowing the poem is in the letter, and this does help to confirm his identity. Bilbo himself recites the poem at the Council of Elrond when Boromir expresses doubts about Aragorn's claim to be the Heir of Isildur.