a proverb

[Freeguy]

I am looking for a proverb (or a famous saying) which states that if you travel to only one country, you will not be able to understand all its features because you haven't seen the other countries, and you cannot make a comparison among them. Or, if you have only read Bible, for example, you will not understand all the nuanced points of it because you need to read other holy books as well.
Do we have a related proverb in English?

[Tarheel]

I am looking for a proverb (or a famous saying) which states that if you travel to only one country, you will not be able to understand all its features because you haven't seen the other countries, and you cannot make a comparison between them. Or, if you have only read the Bible, for example, you will not understand all the nuanced points of it because you need to read other holy books as well.
Do we have a related proverb in English?

Not that I know of.

Do you mean I have to visit every country in a particular area in order to decide which is the most desirable travel destination?

[Freeguy]

Not that I know of.

Do you mean I have to visit every country in a particular area in order to decide which is the most desirable travel destination?

...
Something like that.
If you want to understand the value of something, you should examine the other things of the same kind.

[Tarheel]

Could you give me an example of what that might mean in practical terms?

[Freeguy]

Suppose you want to see a specific grammar book is good or not.
How can you present a fair judge? By examining other grammar books as well.

Do you follow?

[Tarheel]

Suppose you want to determine if a specific grammar book is good or not.
How can you decide? By examining other grammar books as well.

Do you follow?

I think so. But in the case of the grammar book I would decide based on whether the explanations are good and make sense.

You can't visit every country in an area to decide what country to visit. That makes no sense at all. Instead, based on what you want to see, do a little research and decide where it is safe to go and if you can afford to go there.