What authority does the court have to revoke an agreement where an agreement has been signed where the agreement was not revoked?

This position would also appear to be consistent with the authority of Mitchell v. Sykes (1883), 4 O.R. 501 at p. 510, where the court stated: The enquiry is, was there any agreement entered into on sufficient consideration whereby an authority was given for the purpose of securing some benefit to the donee of the authority (the plaintiff) by which he should be enabled to sell the goods he had on failure of the defendant to repay the advances, or to deliver to him goods sufficient to cover his advances? Or was the authority to the plaintiff to sell, on default of the defendant to pay or to secure the advances, given for the purpose of being a security and as a part of the security? Or was there an agreement that there should be an authority to sell in consideration of the advances to be made? In any of these cases the authority to sell cannot be revoked. To determine whether the arrangement between the parties was one within the terms of any of the above propositions it will be necessary to look at the written agreement.