Desire. Simple definition, but surprisingly complex to understand. It is the driving factor for mankind and defines who we are. It has brought mankind knocking on the doorstep of a new age and is going to propel us forward. But as Sir Philip Sidney states in his poem, desires can also lead to negative outcomes and motivate us to desire want ill gains. Sir Philip Sidney elaborates more on the negative side of desires, comparing it to a "blind man's mark".