Answer:
When is 1500 plus 20 and 1600 minus 40 the same thing?
Sitting down you have it, Standing up you don't.
Passed from father to son and shared between brothers, its importance is unquestioned though it is used more by others.
What gets broken without being held?
Hot tempered and sometimes it blows its top, making a mess of everything.
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.