In lieu, therefore, of refusing credit, it is customary with bankers to advance the rate of discount for the purpose of inducing the less necessary credit applications to be withdrawn. The plan in ordinary circumstances is quite successful, since there are always applicants who are on the margin of doubt whether to borrow, or at all events whether to borrow as freely as they are inclined to do. Such applicants are discouraged by the high rate of discount, which takes the profit out of the "marginal" element of their business, and when rates are high and conditions of borrowing stringent they are likely to limit their operations. In very acute conditions of crisis or stringency, however, there is less doubt whether the application even of a rather high rate of discount will be successful. The idea of rationing credit - that is, of investigating the purpose for which applications are made and of granting only those that are definitely necessary - is frequently resorted to as a modification of the plan first suggested - the absolute suspension or refusal of further accommodation. It may be said, however, that the banker's duty is that of continuing to accommodate his customers even in times when his reserve is being seriously infringed upon, and that the very purpose of the reserve itself is to enable him to continue extending this kind of accommodation - that this is, in fact, its highest function, cash being kept on hand for the very purpose of dealing with unusual calls for aid.