Rogers outlines the following six conditions required to exist and continue for constructive personality change to occur
1 - Two persons are in psychological contact.
2 - The first, whom we shall term the client, is in a state of incongruence, being vulnerable or anxious.
3 - The second person, whom we shall term the therapist, is congruent or integrated in the relationship.
4 - The therapist experiences unconditional positive regard for the client.
5 - The therapist experiences an empathic understanding of the client's internal frame of reference and endeavours to communicate this experience to the client.
6 - The communication to the client of the therapist's empathic understanding and unconditional positive regard is to a minimal degree achieved.’
The critical point here is that these conditions are not laying down a framework or a process that leads to a road map for change. The underlying assumption is that the ability to make the necessary change already lies within the client. The core conditionals are essential for supporting the innate impulse of self-actualization to occur.
The analogy that rings most true for me is that of a planted seed. To thrive, become and reach its full potential, the seed has some basic requirements (conditions): sunlight, water and soil. Once these are obtained, though, there is no guarantee that the seedling will still reach its full potential (change), but to be sure, without these conditionals it certainly will not reach its full potential.
It will try, of course, the image Rogers often quoted was of potatoes in a pitch-black cellar far from any soil, but their formative tendency pushed them forward even in a hopeless situation, growing pointless foot-long sprouts, The image powerfully illustrates the notion that the inherent tendency (formative for plants, actualizing for humans) is always there but to reach it's full potential it must have certain core conditions met.
Note also that the potato or seed do not need direction either; they do not need to be taught how to grow or produce shoots or tubers; they innately know their power and the alchemy of their tendency. Similarly, once the core conditions have been met, the focus is not to direct the client on how to grow but to help them explore all that unfolds as they allow the actualizing tendency to flourish into self-actualization.