What is a means of expressing, capturing and permanently holding our most powerful thoughts?
Writing. "If people cannot write well, they cannot think well, and if they cannot think well, others will do their thinking for them." - George Orwell
What is a useful tool to have that can expand and broaden your entire world?
The English Language. English is spoken on every corner of the globe, in every country. No matter where you go, you are bound to encounter the English Language. English is also generally used as a mutual means of communication between two or more people who do not speak the same language. Learning English is a valuable tool that can expand and broaden your entire world because no matter where you go you can rest assured that you will be able to communicate with people easily.
What is something that is universally accepted as a means of common understanding?
The English language. Regardless of where you are, where you go to or where you're from, English will almost always be used as the common language and means of communication between two or more speakers who do not speak the same language.