I want to know the answer to the following question:
IASP's definition of pain includes what aspect as an essential part?
All the background I'm provided with is that "Although unpleasantness is an essential part of the IASP definition of pain, it is possible to induce a state described as intense pain devoid of unpleasantness in some patients, with morphine injection or psychosurgery.". Is that enough to answer the question?