, , ( , ): I = Δ K. .
: ( ) ( ). , ==, .
, ( autonomous investment) ( induced investment). (I = I).
, , , , , . , , .. . (present value - PV) :
1,......n 1,.... n, r ( ).
, , ( ) : I < = PV
, (r) , , .. , , (animal spirit) , ( ), .
, , , , . , , , , ( ) .4.3.