Language exists to communicate ideas, feelings, and action to ourselves and others. Any element of grammar is considered a core element because, without that element, the meaning is lost.
Writers frequently strip their sentences down to find out what is truly needed in that sentence. In doing so, you discover core elements of grammar.
I.e.: Writers strip sentences down to find what is needed in that sentence.
I.e. 2: writers strip sentences to find what is needed.
I think you get my drift.
Sentence diagrams are also incredibly helpful when breaking a sentence down to its core. Check out this site and you see instantly how simple parsing core elements from superfluous elements can be. http://grammar.ccc.commnet.edu/grammar/ ... pager1.htm
Hope this helps!