When it is said that equity presumes prima facie the exercise of undue influence from the circumstances, we mean that, when certain circumstances are shown to have existed, the court will, from that alone, hold that the contract was procured by undue influence, and will relieve the promisor unless the promisee assumes the burden of proof, and shows that everything was fair and just.*2 In some cases the relation alone, being confidential, raises the presumption. In others, the confidential character of the relation must be shown. In others, want or inadequacy of consideration will raise the presumption.48

"We may therefore frame the question we have to discuss somewhat in this way: When a man demands equitable remedies, either as plaintiff or defendant, seeking to escape the effects of a grant which he has made gratuitously, or a promise which he has given upon a very inadequate consideration, what must be shown in addition to this in order to raise the presumption that undue influence has been at work?" **