Here is the original cover of the first edition of “Tame the Flow” book.
In the Divine Comedy poem Inferno by Dante Alighieri (1265 -1321), Phlygeas was the only daemon with the power to cross the river Styx, the river at the boundary between Earth and the Underground. With this power, Phlygeas would ferry the souls of the dead to the Underworld.
In the picture you can see the old bearded man waving an oar over the waves of the river. The man is taming the flow of that furious river! Hence the picture superbly represent the idea of Tame the Flow!