[Systems should be classified] on the basis of the types of inputs with which they must cope. - Robert E. Machol

Sometimes it is more difficult to formulate the criterion for a problem than to state the question itself.

The conclusions of most good operations research studies are obvious.

The ideal system engineer is an engineer thoroughly versed in his field but conversant with and knowledgeable of other fields. You have to have the capability and desire to become a 'six-month expert'... You've got to want to become a generalist, too.