Paraphrase:

In the first place, a contract to create a trust, ie wherein the founder undertakes to transfer the trust property to the trustees at some point in the future, will be governed by its own proper law which may not be the law which governs the trust itself. Likewise, a different law may govern the validity of a will from that which governs the trust thereby created. The ordinary rules governing choice of law in contract and the validity of wills will determine when this divergence takes place.

Initially, a contract establishing a trust where the founder agrees to transfer the trust property to the trustees in the future will be subject to its own specific laws, which may differ from the laws governing the trust itself. Similarly, the law determining the validity of a will may be different from the law governing the trust created by the will. The typical rules concerning the choice of law in contracts and the validity of wills will dictate when this discrepancy occurs.