What is the main thought expressed in this appeal?

The city’s museums are much more than cultural centers. They are major contributors to the city’s economy. Not only do they provide jobs for people living in the city, but also the museums attract tourists who spend money in hotels, restaurants and stores. Each year mass-motoring tours visit our museums and spend millions of dollars in the city, but only a fraction of that money is ever seen by the museums. This, in addition to recent cuts in government aid, has hurt the museums. And museums are in trouble, though we can all help by-increasing our contributions and encourage others to support cultural institutions.  We should help the museums and help ourselves too.  This message is by Crocker Bank, which is interested in keeping New York financially healthy.