&22 Co. [AIR 1965 SC 1591] reiterated as follows: (AIR p. 1593, para 7) “7. … It is essential to bear in mind that the essence of a mortgage by deposit of title deeds is the actual handing over by a borrower to the lender of documents of title to immovable property with the intention that those documents shall constitute a security which will enable the creditor ultimately to recover the money which he has lent. But if the parties choose to reduce the contract to writing, this implication of law is excluded by their express bargain, and the document will be the sole evidence of its terms. In such a case the deposit and the document both form integral parts of the transaction and are essential ingredients in the creation of the mortgage. It follows that in such a case the document which constitutes the bargain regarding security requires registration under Section 17 of the Registration Act, 1908, as a non-testamentary instrument creating an interest in immovable property, where the