for the start of any astrological age and acknowledge that many astrologers believe the Age of Aquarius has arrived while many say the world is at the end of the Age of Pisces. Ray Grasse states in Signs of the Times that "there is considerable dispute over the exact starting and ending times for the different Great Ages." Paul Wright in The Great Ages and Other Astrological Cycles says that much of the uncertainty related to the astrological ages is because many astrologers have a poor understanding of the meaning of the astrological symbolism and "even poorer historical knowledge". Consensus approach Though so many issues are contentious or disputed, there are two aspects of the astrological ages that have virtually unanimous consensus—firstly, the theorized link of the astrological ages to the axial precession of the Earth and commonly referred to as precession of the equinoxes; secondly, that, due to the nature of the precession of the equinoxes, the progression of the ages proceeds in reverse direction through the zodiacal signs. Ages of equal or variable lengths Astrologers use many ways to divide the Great Year into twelve astrological ages. There are two popular methods. One method is to divide the Great Year into twelve astrological ages of approximately equal lengths of around 2156 years per age based on the vernal equinox (also known as vernal point) moving through the sidereal zodiac. Another method is to significantly vary the duration of each astrological age based on the passage of the vernal equinox measured against the actual zodiacal constellations. Each of those twelve sections of the Great Year can be called either an astrological age, Precessional Age, or a Great Month. The method based on the zodiacal constellations has a flaw in that from the reckoning of classical-era astronomer/astrologers like Claudius Ptolemy, many constellations overlap, a problem only eliminated in the past 200 years by the adoption of official constellation boundaries. For example, by 2700 CE the vernal point will have moved into Aquarius, but from a classical-era point of view, the vernal point will also point to Pisces due to the pre-boundary overlap. Age transitions Many astrologers consider the entrance into a new astrological age a gradual transition called a "cusp". For example, Ray Grasse states that an astrological age does not begin at an exact day or year. Paul Wright states that a transition effect does occur at the border