334 A pledge or security stands on its own independent footing, though it is a very convenient form of closing the bargain where the parties cannot trust each other, and cannot get a written agreement with proper witnesses. 335 The Law of Deposit implies great trust in the Depositary on the part of the Depositor. The Depositary becomes a trustee, and the doctrine of Trust can be further developed on that basis. The trustee's duty is to guard the interests of the person on whose behalf he holds the trust and to render back the property and accounts when required according to the terms of the trust. This duty again is linked to the sanction of Religion, which requires a higher standard than Law. 336 It sometimes happens that if some inconvenient piece of evidence is destroyed or concealed, we gain a great advantage materially. We are warned not to yield to such a temptation. The concealment of evidence has a serious effect on our own moral and spiritual life, for it taints the very source of higher life, as typified by the heart. The heart is also the seat of our secrets. We are told that the sin will reach our most secret being, though the sin may not be visible or open to the world. Further, the heart is the seat of our affections, and false dealing taints all our affections.