constrain: “to exert force, physical or moral, upon, either in urging to action or restraining from it,” early 14c., constreyen, from stem of Old French constreindre (Modern French contraindre) “restrain, control,” from Latin constringere “to bind together, tie tightly, fetter, shackle, chain,” from assimilated form of com “with, together” + stringere “to draw tight.”

In essence, Gurdjieff has decided to write because he has little or no choice.