His book, divided in 3 parts, with a long gap during its composition, takes the form of a dialogue between himself and three monk-friends: firstly Ivo, then - much later -Walter and Gratian. This device with its questions and responses enables the author to consider and refine what true spiritual friendship is about.

Daringly, he changes the statement ‘God is love' to ‘God is friendship', an ideal to which all human friendships should aspire. Those friendships which are self-serving or based on flattery or which do not seek the other's greatest good, are rejected as false friendships, to be shunned or terminated. If friendships can be virtuous, for Ælred they can also be ‘vicious'. This is fighting talk, but he is nothing if not human, delighting in ‘companionship of soul' - anam chara (soul-love) in Irish - and recognising that despite human defects, having once received a person in his friendship ‘I cannot do otherwise than love him'. Only betrayal will ruin friendship.

But love, Ælred insists, should remain even when the friendship is destroyed.