When this exists, that comes to be.
With the arising of this, that arises.
When this does not exist, that does not come to be.
With the cessation of this, that ceases.
Although often explained by way of twelve sequential links, dependent origination is not a strictly defined sequence of events in time. It is the conditional interrelation of phenomena, where each event is related to other events by way of cause and effect. Each conditioning factor is at the same time conditioned, without recourse to or need of a transcendent, independent cause.
Two events X and Z, can condition each other when X arises before Z, when X arises simultaneously with Z, and when X arises after Z. X may condition Z by its presence or its absence, and X may relate to Z as cause, as effect, as both effect and cause, or in mutuality.
Understanding dependent origination is the ‘noble method’ to enlightenment.* (1) ignorance, (2) formations, (3) consciousness, (4) name and form, (5) sense media, (6) contact, (7) feeling, (8) craving, (9) clinging, (10) becoming, (11) birth, (12) aging and death