Although depression is often thought of a being an extreme state of sadness, there is a vast difference between clinical depression and sadness. Sadness is a part of being human, a natural reaction to painful circumstances. All of us will experience sadness at some point in our lives. Depression, however, is a physical illness with many more symptoms than an unhappy mood. The person with clinical depression finds that there is not always a logical reason for his dark feelings. Exhortations from well-meaning friends and family for him to "snap out of it" provide only frustration for he can no more "snap out of it" than the diabetic can will his pancreas to produce more insulin. Sadness is a transient feeling that passes as a person comes to term with his troubles. Depression can linger for weeks, months or even years. The sad person feels bad, but continues to cope with living. A person with clinical depression may feel overwhelmed and hopeless.

Depressed mood most of the day, nearly every day, as indicated by either subjective report (e.g. feels sad or empty) or observation made by others (e.g. appears tearful). Children and adolescents may exhibit irritability.

•Markedly diminished interest or pleasure in all, or most, daily activities most of the day, nearly every day.	I'd say it depends on what the activites are and what you know. Take an extreme case: If the activies are to kill people and you know they are innocent. If the activities are meaningless to you. Like cutting grass with pocket knives. (see below) Or let's say you have been relatively happy with your activites, but then you realize you are being used by someone and it all becomes clear to you. Yet you are trapped in the situation.
•Fatigue or loss of energy nearly every day.	This would be understandable if you are not at all motivated to do what you are told, pressured or expected to do; you are being abused; and you actually are powerless to change the situation, such as being in a place you can not leave.
•Feelings of worthlessness or excessive or inappropriate guilt nearly every day.	This could be caused by someone who has power over you, such as a parent, who constantly putting you down, and laying guilt trips on you. Note: See my comments on the word "innapropriate"
•Diminished ability to think or concentrate, or indecisiveness, nearly every day.	This could be caused by things like: - Being trapped in a situation where you are confused by what is happening, such as being told one thing, but seeing the opposite happen. - Having so many worries and fears that you feel overwhelmed. - Being afraid of every possible alternative, such as being afraid to report abuse and being afraid of the abuse continuing.
•Insomnia or hypersomnia (sleeping too much) nearly every day.	Insomnia can be caused by many worries. It is normal to think about things we are afraid of. If we are not getting emotional support...
•Recurrent thoughts of death, recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide.

•Significant weight changes (e.g. a change of more than 5% of body weight in a month), or decrease or increase in appetite nearly every day.

If you are still uncertain as to whether you may be suffering from depression, screening tests exist which can help you determine whether you should seek a professional evaluation. There is a test provided on this site which is simple to use and completely confidential.

A friend told me when he was in the Bulgarian army they ordered the new trainess to cut grass with a pocket knife. This evidently was to help teach them to be obedient, no matter how they felt about the command.