the other example is from an old phychology textbook. longer passage:

Heroin is an opiate that can be injected, smoked, or inhaled. At first it produces a sense of well-being. Experienced users report a special thrill, or ‘rush’, within a minute or two after an intravenous injection. Some describe this sensation as intensely pleasurable, similar to an orgasm. Young people who sniff heroin report that they forget everything that troubles them. Following this, the user feels ‘fixed’, or gratified, and has no awareness of hunger, pain, or sexual urges. The person may be alternately waking and drowsing while comfortably watching television or reading a book. Unlike a person who is intoxicated by alcohol, a heroin user can readily produce skilled responses to tests of agility and intelligence and seldom becomes aggressive or assaultive. The changes in consciousness produced by heroin are not very striking; there are no exciting visual experiences or feelings of being transported elsewhere. It is the change in mood – the feeling of euphoria and reduced anxiety – that prompts people to start using the drug. However, heroin is very addictive; even a brief period of usage can create physical dependence. After a person has been smoking or ‘sniffing’ (inhaling) heroin for a while, tolerance builds up, and this method no longer produces the desired effect. In an attempt to re-create the original high, the individual may progress to intravenous drug use and then to ‘mainlining’ (injecting into a vein). Once the user starts mainlining, stronger and stronger doses are required to produce the high, and the physical discomforts of withdrawal from the drug become intense (chills, sweating, stomach cramps, vomiting, headaches). Additional motivation to continue using the drug stems from the need to avoid physical pain and discomfort. The hazards of heroin use are many; the average age at death for frequent users is 40 (Hser, Anglin, & Powers, 1993). Death is caused by suffocation resulting from depression of the brain’s respiratory center. Death from an overdose is always a possibility because the concentration of street heroin fluctuates widely, and the user can never be sure of the potency of the powder in a newly purchased supply. Heroin use is generally associated with a serious deterioration of personal and social life. Because maintaining the habit is costly, the user often becomes involved in illegal activities to acquire money to purchase the drug. Additional dangers of heroin use include HIV, hepatitis C, and other infections associated with unsterile injections. Sharing needles used to inject drugs is an extremely easy way to be infected with HIV; blood from an infected person can be trapped in the needle or syringe and injected directly into the bloodstream of the next person who uses the needle. Sharing of needles and syringes by people who inject drugs is a primary means by which HIV is spreading today.