When Porter J. Goss resigned on Friday as director of the C.I.A., he found himself in good company. In one way or another, the job of C.I.A. chief has confounded nearly every man who has held it.

With few exceptions, each of the 19 directors of central intelligence has resigned in frustration, given his walking papers by the president or been pressured out of the agency's headquarters seven miles up the Potomac from the White House.

"Here is one of the most peculiar types of operation any government can have," President Dwight D. Eisenhower once said. "It probably takes a strange kind of genius to run it."