If a spiritual mentor lacks realisation, it does not help even if his disciples act with reverence and devotion. As an analogy, although the clay may be good, if its mold has no indentations, it will not form into a statue. If the disciples have no reverence or devotion, it does not help even if the spiritual mentor has realisation. This is like a cow having milk, but its calf having no palate. 

-- Gampopa