Cultures have long heard wisdom in non-human voices: Apollo, god of music, medicine and knowledge, came to Delphi in the form of a dolphin. But dolphins, which fill the oceans with blipping and chirping, and whales, which mew and caw in ultramarine jazz - a true rhapsody in blue - are hunted to the edge of silence.

Meaning: Someone's belief may have been produced by what they want to be true, rather than by good evidence that it is true.

Meaning: An outward container does not establish the quality of what is inside. Look for evidence about the substance rather than relying on packaging, appearance or a reassuring presentation.

Meaning: A request made at a higher level leaves room to reduce it later. The saying describes flexibility in an opening demand, while its advice needs limits: an inflated request can undermine trust or ignore what the other person can reasonably offer.

Meaning: A measure can register one property without recognising the differences that matter for another judgement. Equal weight does not mean equal value; choose evidence suited to the question.