If you don't go into the tiger's den, how can you get first-hand information? He decided to go to the scene himself.
Tips
usage
The first half of 不入虎穴,焉得虎子, 'if you don't go into the tiger's den, how will you catch its cub?', said before taking a risk for a big gain. Often only this half is spoken, and the speaker ends the sentence with a question of their own.
history
The 后汉书 gives the saying to the general 班超, who used it to rally his 36 men for a night attack on a far larger Xiongnu embassy in the kingdom of 鄯善.