It's about choosing happiness and accepting that this means accepting some measure of illusion as well. He goes past those "shadows dark and deep" without entering them. He realizes the facts of the universe that his life will end, flowers bend with the rainfall, and his reflection just shows a small and dark figure. He admits to being blinded and wandering without direction, but he's already demonstrated self-awareness of his self-deception. Whether you're at the top or the bottom of society, you could go to either joy or sorrow, it's all about mindset. So he forms this fantasy, makes it become reality so he can face the world with a smile.
It's about choosing happiness and accepting that this means accepting some measure of illusion as well. He goes past those "shadows dark and deep" without entering them. He realizes the facts of the universe that his life will end, flowers bend with the rainfall, and his reflection just shows a small and dark figure. He admits to being blinded and wandering without direction, but he's already demonstrated self-awareness of his self-deception. Whether you're at the top or the bottom of society, you could go to either joy or sorrow, it's all about mindset. So he forms this fantasy, makes it become reality so he can face the world with a smile.