not mean what he clearly said, or that he should be excused from performance because the contract did not work out in the manner expected by one or even by both of the parties.
(iv) That which is to be ascertained, not necessarily from the terms of the contract, but from any surrounding circumstances of which the parties were aware, is 'the substance of the contract."
I am not sure whether the substance of the contract, when ascer- tained, is a kind of basis or foundation upon which the contract stands, or whether, on the other hand, it is something which is imported into the contract as one of its terms. If the former is the true meaning of what is said, then though a contract consists of (and only of) the terms upon which the parties have chosen to agree, there is or may be something else, dehors the contract, which is the "foundation" of the contract; if the foundation of the contract fails, then the whole of the contract, which stands upon the pedestal provided by such a foundation, is thereafter completely destroyed. If, on the other hand, the meaning of the expression is that another "substantial" term, derived from consideration of "surrounding circumstances," may in some cases properly be implied by a court, then the "basis of the contract" theory of frustration is indistin- guishable from the "implied term' theory-to which I refer here- after.
(v) When the "substance" of the contract is ascertained, it is then necessary to ask the question "whether that substantial contract needs for its foundation the assumption of the existence of a particular state of things." Such a "foundation" is not to be discovered in the terms of the contract in which the parties have expressed their intentions. It is to be ascertained by the court, presumably as a "necessary" inference from "surrounding circum- stances."
(vi) The result of all these considerations is to limit the operation of the general words." The consequence, therefore, is that the words in the contract must be treated as meaning something other than that which they appear to mean, because they are subject to some unexpressed limitation or condition.
(vii) If the operation of the general words is limited by reason of the foregoing considerations, then if the contract becomes impos- sible of performance by reason of the non-existence of the state of things assumed by both contracting parties as the foundation of the contract" a certain result happens. Thus impossibility of per- forming the contract is regarded as the crucial consideration.
Impossibility of performing a contract according to its expressed terms is a very common case. As a rule, when two persons make