In May 2007, I stood down as leader of the DA after seven years as its head and, six years before that, as the leader of its predecessor movement, the Democratic Party. Thirteen exhilarating, exhausting and often hair-raising years at the crease was quite enough for me, the party and doubtless for the country as well.On Sunday the person who was elected as the second leader of the DA, Helen Zille, announced that she would be retiring next month as party head at the DA congress.There is, as she observed, nothing in the party rule book that limits the leader's term of office. She could, like "iron lady" Margaret Thatcher, who had the bigger job of running a significant country, have attempted to go "on and on". But we all know where that ended - in tears and with a stab in the back. It probably took the British Conservative Party the best part of two decades to recover, if indeed it ever has.Back at home, the ANC's overthrow of Thabo Mbeki traumatised the movement and inflicted huge damage on an array of institutions, if not the constitution itself. We are living with the consequences of that today.By comparison, Zille's decision seems both timely and commendable.When I wrestled with the same decision more than seven years ago, I remembered the parting words of the successful Springbok rugby captain Morné du Plessis. When asked why he was retiring, he responded: "Better that people ask why I am leaving the field rather than why I am still on it."And whatever a leader's successes and failures, it is quite striking how relatively quickly political capital gets diminished. Every tough decision brings in its wake recrimination; every person promoted leaves another with dashed expectations. Every principle adjusted to compromise leads to the label "sell out". And so it goes, unless the leader ducks the difficult calls, in which case their leadership will be a real failure anyway.So new leadership allows a chance for a political party to refresh itself and renew its relevance.But as Karl Marx observed: "Men make their own history, but they do not make it as they please."There are no truer words for the third DA leader, who will inherit sizeable political real estate: a well-organised party machine, control of the Western Cape and thousands of public representatives.But it could be argued that the DA is worse off than in 1994 as at that time the parties that formed the DA, the DP and the National Party, had between them a deputy president and six cabinet ministers in government.At first blush, some would describe the party's position as "dynamic stagnation". It has grown market share but has stood still. This, of course, ignores one huge demographic fact.The DA today has grown from nowhere in black areas to reach a foothold in many previous no-go zones. Due to mortality and migration, the DA has lost much of its core white (and coloured) support base. Replacing this original base with a new one has meant that the DA has had to make significant gains simply to stand still.The new DA leader will have to deal with one consequence of the party's current and perhaps future base: propping up this diverse demographic tent and keeping it standing .In contrast, the ANC has essentially written off electoral minorities and vice versa.But it still has the support of the majority.For the DA, its commendable diversity brings its own set of problems. Some of its white and coloured members, who feel overlooked or differently treated, say "we bring most of the party votes and funds". The response of some black members and new leaders will be: "But we represent the future."The problem for the new leader is not that both of these claims are wrong, but that both are partly correct.Of course the party stands for non-racialism and equality of opportunity not outcomes, but the current cultural wars sweeping the country show just how difficult it is to translate, or even articulate, this as principle.And should principle be advanced at the risk of alienating new voters, or be ducked and then annoy existing ones, or the other way round? That is the core of the leader's job: To give clear direction based on clear beliefs.The Rhodes Must Fall campaign at UCT brought this into sharpest relief. DA MP Michael Cardo denounced the university senate for green-lighting the statue's removal; the party's campus organisation, DASO, gave its "full support", and the DA's leadership shuffled its feet on the issue.Perhaps trying to square this and other endless circles tired Zille. But her successor will need to offer a clear voice and view on these burning issues.Doing so based on core principles fashioned to meet the challenges of today could mean more success for the party. On the other hand, following the path of least resistance always, over time, leads downhill...