A Touch of Terror
A touch of terror gives the stamp of validity to an experience because it means, "This is real." We are in the balance. We read the literature, we know the maximum doses, the LD-50 and so on. But nevertheless, so great is one's faith in the mind that when one is out in it one comes to feel that the rules of pharmacology do not really apply and that control of existence on that plane is really a matter of focus of will and good luck.
I'm not saying that there is something intrinsically good about terror. I'm saying that, granted the situation, if one is not terrified then one must be somewhat out of the full dynamics of what is happening. To not be terrified means that one is either a fool or that one has taken a compound that paralyses the ability to be terrified. I have nothing against hedonism, and I certainly bring something out of it. But the experience must move one's heart, and it will not move the heart unless it deals with issues of life and death. If it deals with life and death then it will move one to fear, it will move one to tears, it will move one to laughter. These places are profoundly strange and alien.
Terence McKenna from the article 'Tryptamine Hallucinogens and Consciousness", full article at deoxy.org/t_thc.htm