Water

“You cannot see your reflection in boiling water. Similarly, you cannot see the truth in a state of anger. When the waters calm, clarity comes.” 

Is this from a film I never heard of called Kung Fu Panda?

"Calm the muddy water, 

It becomes clear." 

Tao Ti Ching

“However deep you dig a well it affords no refuge in the time of flood.” 

Ernest Bramah, Kai Lung Unrolls His Mat 

"As water reflects the face, so one’s life reflects the heart." Proverbs 27:19

"In calm water, every ship has a good captain." 

 Swedish proverb

“Thousands have lived without love, not one without water.” 

W.H. Auden

“If a man knows not to which port he sails, no wind is favourable.” Seneca. Lord Heseltine's favourite quotation, though he has read little (he's dyslexic) and certainly not much of the classics. England has been ruled since Macmillan retired mostly by badly read men and women, though Boris does know the classics.