Disclaimer- I don't own Inuyasha.
Like all children, Miroku did not understand many things.
He did not understand why there were poor people begging for scraps and rich people who were fat and lazy.
He did not understand why his father, who was dying a little every day, chose to spend much of his time scamming the rich, drinking and spending time with women, and occasionally even doing good deeds.
And like all children, he asked questions.
"Father? Why do you do these things?" he asked quietly, his voice low and curious.
His father turned towards him with a smiling eye. "My boy, you must learn to enjoy the pleasures of life, and not be concerned with your fate."
"But you are dying father! The Kazaana-" Miroku said pleadingly, his voice the desperation only a helpless child could know.
"Is a curse," his father interrupted, "placed on us by Naraku. I'm quite aware of that, Miroku." He said, reproach thick in his voice, causing the boy to flinch in response.
Then his eyes softened, and he bent forward, looking his son in the eye. "And that is why I choose to live. Because Naraku would want us to suffer, to agonize over every swiftly passing moment of our lives."
He looked at his son, and watched the troubled look linger, and spoke again. "Son, even if I did not posses the Kazaana, I would die sooner or later, either to a demon or to old age. Death is not your enemy. Death is merely a continuation on the journey of existence."
"I don't understand," Miroku said stubbornly. "We could be hunting Naraku down and catch up to him so much faster if you would only-"
His father shushed him with a quiet whisper. "Naraku is elusive, my son. But as I told you before, he will die, whether by my hand, your hand, or by another's, and we will be free." There was a certain gentle wisdom in his voice that Miroku envied. "And should we die, we will still be free of this mortal coil and this Kazaana."
"So you're saying it doesn't matter if we kill Naraku or not!" Miroku challenged, his voice still filled with the stubborn resistance of a child.
Shaking his head, his father merely looked at him with unaffected patience. "Nay, son. It does matter a great deal to me if I kill Naraku." The look he gave Miroku told the boy that his father was thinking of him as he spoke.
Feeling chastised despite no harsh words from his father, Miroku looked downwards, abashed. "I still don't understand," he murmured, confusion quieting his voice.
"I don't expect you to yet," his father replied calmly, "But Naraku is a cruel monster, and revels in our suffering from this Kazaana. He wants us to be afraid, to cut ourselves away from life and be consumed by hatred and despair."
The smile was serene and gentle. "By living, Miroku, we fight Naraku every day."