What description of Phebe's character can we derive from Rosalind in Act 4, Scene 3 of Shakespeare's As You Like It?
Rosalind as Ganymede spends a great deal of time characterizing Phebe through the letter Phebe has Silvius deliver to Ganymede in Act 4, Scene 3. At first, Rosalind teases Silvius by pretending that the letter is an irate attack on Ganymede, calling Ganymede ugly, rude, and proud. Rosalind does this with the purpose of portraying Phebe as being cruel, even saying that Phebe wrote the letter in a "boisterous and a cruel style" (31). However, the reality is that the letter Rosalind is reading is actually a love poem Phebe wrote to Ganymede. Rosalind then proceeds to read the poetry, even the opening lines asking Ganymede why he gave up his "godhead" to take up the form of a shepherd and break a woman's heart. She even reads Phebe's declaration that if Ganymede does not accept Phebe's love, Phebe will die, as we see in the lines:
Will the faithful offer take
Of me and all that I can make;
Or else by him my love deny,
And then I'll study how to die (60-63)
However, Rosalind's true motive for reading the letter is to, again, show Silvius just how cruel Phebe is being. We especially learn Rosalind's true motive when Celia proclaims pity on Silvius and Rosalind's response is to declare that he deserves no pity for loving such a cruel woman as Phebe, a woman who even lied to him about the contents of the letter to manipulate him into delivering her love letter to Ganymede.
Hence, in this scene, Rosalind essentially uses her wise sense of humor and Phebe's letter to describe and characterize Phebe as a cruel and selfish woman who is not worthy of Silvius's love.