One cannot be successful on visible figures alone ... the most important figures that one needs for management are unknown or unknowable, but successful management must nevertheless take account of them.

There is no substitute for knowledge.

We should be guided by theory, not by numbers.

The job can't be finished only improved to please the customer.

Failure of management to plan for the future and to foresee problems has brought about waste of manpower, of materials, of the machine-time, of all which raise the manufacturer's cost and price that the purchaser must pay

A system can not understand itself.

You must have a supplier relationship of constant improvement.