For they attributed to the king of old all their essential laws; and usually they kept the laws of free will, because they were The Rules (as they said), both ancient and just.
It was written long before the foreshadow of 1939 had yet become a threat of inevitable disaster, and from that point the story would have developed along essentially the same lines, if that disaster had been averted.
It is an essential part of the plot, foreseen from the outset, though in the event modified by the character of Saruman as developed in the story without, need I say, any allegorical significance or contemporary political reference whatsoever.
There are no more uses of "essential" in the book.
Show samples from other sources
The essential feature of the pen is that it writes so consistently.
I carry all the essential tools and materials I need in this toolbox.