Step 1: Understanding the context.
The Maharaja wanted to give his son a meaningful and memorable gift on his third birthday. He decided to bring a special gift that would serve as a symbol of his love and care for his son.
Step 2: Description of the gift.
The gift the Maharaja brought for his son on his third birthday was a beautiful white horse. This horse was not just an ordinary gift, but a prized possession, symbolizing the Maharaja's wealth, affection, and his desire to present something significant on such an important occasion.
Step 3: The importance of the gift.
This gift reflected the Maharaja's deep connection with his son, as well as the cultural significance of horses as a mark of prestige and grandeur in their royal life.
Final Answer: \[ \boxed{\text{The Maharaja brought a beautiful white horse as a gift for his son's third birthday, symbolizing wealth, love, and the significance of the occasion.}} \]