In 1961 Robert Heinlein's book A Stranger In A Strange Land was published,. It is the sci-fi story of Valentine Smith, a human raised on Mars by Martians and his difficult interaction with humans on return to Earth. 'Stranger in a strange land' is one of the items mentioned in Billy Joel's We Didn't Start the Fire.
Heinlein coined the term "grok" for the novel, a Martian concept that is hard to define in Earthly terms. In the novel it is described as:
Grok means to understand so thoroughly that the observer becomes a part of the observed—to merge, blend, intermarry, lose identity in group experience. It means almost everything that we mean by religion, philosophy, and science—and it means as little to us (because of our Earthly assumptions) as color means to a blind man.
The above meaning - to understand something so well that it becomes part of you - is also explained in the novel as "to take it all in," to understand fully, or to "be at one with." Others have explained it as to understand fully by intuition and empathy. The word has become favoured by computer geeks and sc fi fans. You can even buy T shirts bearing the words 'I grock Spock".
The Urban Dictionary also provides "to become one with" as a meaning, which gives me the excuse to ask: What did the Buddhist monk say to the hot dog vendor? Answer: Make me one with everything.