Introduction:
In the story "The Happy Prince" by Oscar Wilde, the swallow plays a significant role in conveying the prince's compassion for the poor and needy. The swallow acts as the prince's messenger, carrying out his kind deeds and becoming a witness to his empathy towards those who suffer.

The Swallow Discovers the Prince's Compassion:
1. Initial Encounter:
- The swallow first encounters the prince while seeking shelter from the cold winter night.
- The prince's statue is adorned with precious jewels and gold, reflecting his former luxurious life.
- However, the swallow notices the prince's tears and asks why he is weeping.
- The prince reveals that he can see the suffering of the poor from his elevated position.

2. The Swallow's Curiosity:
- Intrigued by the prince's tears, the swallow decides to stay and listen to his story.
- As the prince shares his observations of poverty and despair, the swallow becomes aware of his deep empathy towards the less fortunate.

3. The Swallow Becomes the Prince's Messenger:
- The prince asks the swallow to assist him in alleviating the suffering of the poor.
- The swallow selflessly agrees and carries out various acts of kindness on behalf of the prince.
- Through these acts, the swallow witnesses firsthand the prince's compassion for the poor and needy.

4. Examples of the Prince's Compassion:
- The prince instructs the swallow to pluck out his sapphire eyes and distribute them to the poor.
- He directs the swallow to take his gold leaf and give it to a poor playwright so that he can buy food for his family.
- The prince also orders the swallow to deliver his ruby heart to a sick boy, saving his life.

The Swallow's Observations:
1. The Swallow's Emotional Connection:
- As the swallow carries out the prince's instructions, he develops an emotional bond with the prince.
- This bond deepens as he witnesses the prince's selflessness and genuine concern for others.

2. The Swallow's Reflection:
- Through his experiences with the prince, the swallow realizes that true happiness lies in sacrificing for others.
- He acknowledges the prince's compassionate nature and understands the importance of empathy and kindness.

Conclusion:
The swallow discovers the prince's compassion for the poor and needy through their interactions and the acts of kindness the prince directs him to perform. The prince's tears, his instructions to help the less fortunate, and the swallow's emotional connection with him all serve as evidence of the prince's deep empathy and concern for those in need.