Four things that give mankind a shove Are threats, exchange, persuasion, love

From Kenneth Boulding in Towards a Pure Theory of Threat Systems, an article in The American Economic Review, Vol. 53, No. 2, (May, 1963), pp. 424-434

Four things that give mankind a shove 

Are threats, exchange, persuasion, love; 

But taken in the wrong proportions 

These give us cultural abortions. 

For threats bring manifold abuses 

In games where everybody loses; 

Exchange enriches every nation 

But leads to dangerous alienation; 

Persuaders organize their brothers 

But fool themselves as well as others; 

And love, with longer pull than hate, 

Is slow indeed to propagate.