From Security Analysis,
1940 edition:
“The essential point is that security analysis does not seek
to determine exactly what is the intrinsic value of a given security. It needs
only to establish either that the value is adequate—e.g.,
to protect a bond or to justify a stock purchase—or else that the value is
considerably higher or considerably lower than the market price. For such purposes
an indefinite and approximate measure of the intrinsic value may be sufficient.
To use a homely simile, it is quite possible to decide by inspection that a
woman is old enough to vote without knowing her age or that a man is heavier
than he should be without knowing his exact weight.”