“12…… In other words, if the Power of Attorney Holder has rendered some „acts‟ in pursuance of power of attorney, he may depose for the principal in respect of such acts, but he cannot depose for the principal for the act done by the principal and not by him. Similarly, he cannot depose for the principal in respect of the matter of which only the principal can have personal knowledge and in respect of which the principal is entitled to be cross-examined . If a plaintiff, in a suit for specific performance is required to prove that he was always ready and willing to perform his part of the contract, it is necessary for him to step into the witness box and depose the said fact and subject himself to cross-examination on that issue. A plaintiff cannot examine in his place, his attorney holder who did not have personal knowledge either of the transaction or of his readiness and willingness. The term „readiness and willingness‟ refers to the state of mind and conduct of the purchaser, as also his capacity and preparedness, one without the other being not sufficient. Therefore, a third party having no personal knowledge about the transaction cannot give evidence about the readiness and willingness.”