The distinctions between the contract of the surety and the guarantor have already been observed in section four of this text, and it will be remembered that the guarantor's contract is both a collateral one, and also a secondary one to the principal's contract, the guarantor's promise usually amounting to this, that he will answer for the principal's default, provided the principal does not respond, and the creditor observe the rule of due diligence, the use of which the creditor is bound to undertake in accordance with the terms of the contract. In addition to this, it may be said the guarantor's contract being a secondary one, it requires a special consideration to support it; the principal's contract is not the guarantor's. The guarantor must therefore have notice of the principal's default, and good faith requires that the creditor who fails to give such notice is acting at his peril. The guarantor can claim a discharge to the extent of the injury he suffers, by reason of failure to receive notice, where the lack of notice of default on the part of the creditor materially affects him in his rights under the contract.