These words refer to an inability to act in one’s own behalf. Powerless indicates an inability to act because of outside resistance. Helpless , by contrast, suggests someone incapable of action because of his own inadequacy, without reference to externals. These distinctions are completely at variance with what both words might seem to suggest (lack of power; lack of external help): a decision by his superiors that left him powerless to act; helpless as an infant who must be nursed and watched every second of the day. Both words can, of course, be used in the context more appropriate to the other; helpless , especially, can refer to someone literally without aid or assistance: a last survivor who was helpless to prevent the Maoris from capturing the fort.

Paralysed in this context compares an inability to act with muscular disablement; impotent here compares the same inability to sexual disablement. Both words suggest a will or desire to act that some other impulse has contravened: a mind paralysed by its own excessively fine distinctions; embarrassment that rendered her impotent to speak. Both words can also refer to a will made powerless or a normal routine frustrated by external forces: a city paralysed by the striking union; red tape that left the chairman impotent to innovate or experiment. Paralysed is the more intense of these two words, suggesting a greater crisis and a greater difficulty of resolution. The sexual metaphor inherent in impotent is always in danger of surfacing and making the word sound unintentionally comic in this context.