I am the center of gravity, hold a capital situation in Vienna, and as I am
foremost in every victory, am allowed by all to be invaluable. Though I am
invisible, I am clearly seen in the midst of a river. I could name three who are
in love with me and have three associates in vice. It is vain that you seek me
for I have long been in heaven yet even now lie embalmed in the grave. What am
I?