Balance

The symbolism of DNA and the scale are used to convey the idea of a mixture that is in flux and wants to archive balance. This card is usually called 'temperance' which conceptually conveys the idea of balance and moderation. There is an association of the word 'temperance' with Christian abstinence, so to universalize the nomenclature, the words 'harmony' and 'balance' are used instead of 'temperance'. The 'Temperance Society' formed in 1835 was Catholic in origin and advocated teetotalism and abstinence rather than moderation in all things.
The 'real' concept of 'temperance' or 'moderation' is germain in most moral behavior models. Held as one of the four virtues in Hellenic society, one of the five precepts of Buddhism, and one of the key tenets in Christianity, and Hinduism, moderation in practice means "...governing natural appetites for the pleasure of senses according to the bounds of reason." (Wikipedia) So when this card appears in a reading, outside spiritual forces are reminding us to control our behavior in favor of the balanced path.