I think frog haven't introduced himself as Mozart but Nightingale thought that he is like Mozart for her.

The frog in the poem "The Frog and the Nightingale" introduces himself as Mozart to impress the Nightingale and gain her trust.

Reasoning behind the Introduction:

1. To appeal to the Nightingale's love for music: The frog knew that the Nightingale was a talented singer and therefore introduced himself as a renowned composer, Mozart, to impress her and to make her believe that he was knowledgeable about music.

2. To establish authority: The frog knew that he could only control the Nightingale if she believed that he was superior to her in some way. By introducing himself as Mozart, he established his authority in the field of music and made the Nightingale believe that she had something to learn from him.

3. To manipulate the Nightingale: The frog was aware of the Nightingale's naivety and used it to his advantage. He knew that by pretending to be someone whom the Nightingale admired and respected, he could manipulate her into doing what he wanted.

Conclusion:

The frog's introduction as Mozart was a calculated move to establish his authority over the Nightingale and manipulate her into singing for him. However, his true intentions were revealed when he criticized her singing and suggested that she needed his guidance to improve. This ultimately led to the Nightingale's downfall, highlighting the dangers of blindly trusting those who claim to be experts.