Legally speaking, a contract need not be in writing. However, regarding the contract of employment, there must be an offer of appointment unconditionally accepted by the other party, both in written form. An affidavit does not add any evidentiary value. An affidavit only serves the purpose of identifying the deponent (the swearer of the affidavit) by the person named therein, and the notary attests to the signature as having been made in his presence; it offers no proof of its contents. Therefore, a valid contract can be formed by the exchange of two pieces of paper, one detailing the offer made and the other conveying its unconditional acceptance.