This is because the concrete particular is an aggregate and is made up of different temporal parts. This means that if the candle existed yesterday, and it exists today, it is not the same candle because the candle exists through time, not at specific times. It is still a candle, yet it is made up of spatial parts, which at times these parts overlap. .
As aforementioned perdurantists belives that concrete particulars are four-dimensional. Time, is simply, another dimension coupled with the three spatial dimensions. Perdurantists believe that concrete particulars take up not only space, like you will see the enduranists also believe, but they also take up time. Thus the reason for them being made up of temporal parts.
A perduransists account of time is the present. For example an object now and five seconds from now are two totally different times, however the object now is made up of the part of what it was five second earlier. They believe that things can only exist in the now, what they were before is something different than what they are now, but can contain parts of what they once were. Again, this goes back to their belief in temporal parts making up a whole. All things cannot wholly exist in the now, but can be made of temporal parts that through time would allow them to form a whole. .
Perdurantists also claim that at all times all things existing at those times are equally real. Just because an object is not wholly existing in the now does not mean that it is not real. It is real, but is merely a portion of their whole realness. The objects that are in the now, only exist in the now, but can have temporal parts, which allow for them to be temporally whole. The main point that needs to be understood about perdurantists is that they believe objects exist in the now, but only partly exist, but even though they only partly exist, they are still real.
On the opposing side of the issue, the endurantists, or three-dimensionalists, claim that for a concrete particular to persist through time it must exist wholly and completely at different times.
