To find out
Examples
The best way to find out if you can trust somebody is to trust them.
I myself have never been able to find out precisely what feminism is: I only know that people call me a feminist whenever I express sentiments that differentiate me from a doormat.
The best way to give advice to your children is to find out what they want and then advise them to do it.
If you want to find out about the road ahead, then ask about it from those coming back.
It is a great point of wisdom to find out one's own folly.
If you do not strike back at him who hits you, there is no way for him to find out whether you also have hands.