[T]o the human mind there is more to blood than its mere chemical content. … For example, blood must essentially be thicker than water, impossible to get out of stones, indelible in its staining. … When apparent on heads, it should leave them unbowed; and should have the capacities to combine formidably with toil, tears and sweat and to attain boiling-point when its host faces frustration.

— Patrick Ryan, in New Scientist