In the late 19th century, in the early days of Zionism, Rabbi Yitzchak Elchanan Spektor came up with a halakhic means of allowing agriculture to continue during the Shmita year. After ruling in favor of "Minhag Yerushalayim", that the biblical prohibition consists of not cultivating the land owned by Jews (""your" land", Exodus 23:10), Rabbi Spektor devised a mechanism by which the land could be sold to a non-Jew for the duration of that year under a trust agreement. Under this plan, the land would belong to the non-Jew temporarily, and revert to Jewish ownership when the year was over. When the land was sold under such an arrangement, Jews could continue to farm it. Rabbi Abraham Isaac Kook, the first Chief Rabbi of British Mandate Palestine, allowed this principle, not as an ideal, but rather as a limited permit for individuals and times which are considered by Halacha of great need ("b'shas hadchak"), which became known as the "heter mechira" (lit. "sale permit"). Rabbi Kook explained in a lengthy responsum that the ideal is not to rely on the leniency of heter mechira, but rather to observe shmita according to all opinions. He noted that he himself did not rely on the leniency, it was intended only in a limited time of great need, for those unable to observe the shmita without the leniency.