Explain

Art. 1356, Contracts shall be obligatory in whatever form they may have been entered into, provided all the essential requisites for their validity are present. x x x.\" These essential requisites last mentioned are normally: (1) consent, (2) proper subject matter, and (3) consideration or causa for the obligation assumed (Article 1318). So that once the three elements exist, the contract is generally valid and obligatory, regardless of the form, oral or written, in which they are couched. To this general rule, the Code admits exceptions, set forth in the second portion of Article 1356: \"However, when the law requires that a contract be in some form in order that it may be valid, or enforceable, or that a contract be proved in a certain way, that requirement is absolute and indispensable. x x x.\" It is thus seen that to the general rule that the form (oral or written) is irrelevant to the binding effect inter partes of a contract that possesses the three validating elements of consent, subject matter, and causa, Article 1356 of the Code establishes only two exceptions, to wit: a) Contracts for which the law itself requires that they be in some particular form (writing) in order to make them valid and enforceable (the so-called solemn contracts), Of these the typical example is the donation of immovable property that the law (Article 749) requires to be embodied in a public instrument in order \"that the donation may be valid,\" i.c., existing or binding. Other instances are the donation of movables worth more than P5,000.00 which must be in writing, \"otherwise the donation shall be void\" (Article 748); contracts to pay interest on loans (mutuum) that must be \"expressly stipulated in writing\" (Article 1956); and the agreements contemplated by Articles 1744, 1773, 1847 and 2134 of the present Civil Code. b) Contracts that the law requires to be proved by some writing (memorandum) of its terms, as in those covered by the old Statute of Frauds, now Article 1403(2) of the Civil Code. Their existence not being provable by mere oral testimony (unless wholly or partly executed), these contracts are excep-tional in requiring a writing embodying the terms thereof for their enforceability by action in court. The contract sued upon by petitioner herein (compensation for services) does not come under the exception. x x x. In Cenido vs. Apacionado,'* the Supreme Court upheld the vali- dity of a-written contract of sale of real property even if it were not in a fablombtHinent demande, AHeTeMSRAHAL requisites of the