There is a tide in the affairs of men.
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
On such a full sea are we now afloat,
And we must take the current when it serves,
Or lose our ventures.
—Shakespeare, Brutus in Julius Caesar Act 4, scene 3, 218–224
i.e.:Take the current when it flows in your direction....