There is a popular quote from the famous novel The Little Prince:
What is essential is invisible to the eye.
The Japanese translation goes something like this:
I have three questions: First, invisible is "cannot be seen". Why is 見えない used instead of 見られない？
Second, what does it mean when you put: んだ in the end of the sentence? For me i wouldnt have thought about it and could have ended with みられない。
Third, 大切 is important. Since the word used in the text is essential, is it possible that there is a better word for that? Something that is one level higher than just being important? Perhaps a level like 欠かせない。