One of the most brilliant aspects of Le Nôtre’s concept was the use of an optical illusion known as ‘anamorphosis abscondita’, resulting in decelerated or accelerated perspective according to whether the gardens were viewed away from, or towards the château. This was achieved by means of visual devices that rendered ovular pools as circular, and changed the apparent level of the grottoes at the far end of the park, by means of an optical effect based on the tenth theorem of Euclid’s optics - Andrew Lyndon Skeggs
Le Nôtre employed an optical illusion called anamorphosis abscondita (which might be roughly translated as 'hidden distortion') in his garden design in order to establish decelerated perspective. The most apparent change in this manner is of the reflecting pools. They are narrower at the closest point to the viewer (standing at the rear of the château) than at their farthest point; this makes them appear closer to the viewer. From a certain designed viewing point, the distortion designed into the landscape elements produces a particular forced perspective and the eye perceives the elements to be closer than they actually are. That point, for Vaux-le-Vicomte, is at the top of the stairs at the rear of the château. Standing atop the grand staircase, one begins to experience the garden with a magnificent perspectival view. The anamorphosis abscondita creates visual effects, which are not encountered in nature, making the spectacle of gardens designed in this way extremely unusual to the viewer (who experiences a tension between the natural perspective cues in his peripheral vision and the forced perspective of the formal garden). The perspective effects are not readily apparent in photographs, either, making viewing the gardens in person the only way of truly experiencing them.
From the top of the grand staircase, this gives the impression that the entire garden is revealed in one single glance. Initially, the view consists of symmetrical rows of shrubbery, avenues, fountains, statues, flowers and other pieces developed to imitate nature: the elements exemplify the Baroque desire to mold nature to fit its wishes, thus using nature to imitate nature. The centrepiece is a large reflecting pool flanked by grottos holding statues in their many niches. The grand sloping lawn is not visible until one begins to explore the garden, when the viewer is made aware of the optical elements involved and discovers that the garden is much larger than it looks. Next, a circular pool, previously seen as ovular due to foreshortening, is passed and a canal that bisects the site is revealed, as well as a lower level path. As the viewer continues on, the second pool shows itself to be square and the grottos and their niched statues become clearer. However, when one walks towards the grottos, the relationship between the pool and the grottos appears awry. The grottos are actually on a much lower level than the rest of the garden and separated by a wide canal that is over half a mile (almost a kilometre) long. According to Allen Weiss, in Mirrors of Infinity, this optical effect is a result of the use of the tenth theorem of Euclid's Optics, which asserts that "the most distant parts of planes situated below the eye appear to be the most elevated".
In Fouquet’s time, interested parties could cross the canal in a boat, but walking around the canal provides a view of the woods that mark what is no longer the garden and shows the distortion of the grottos previously seen as sculptural. Once the canal and grottos have been passed, the large sloping lawn is reached and the garden is viewed from the initial viewpoint’s vanishing point, thus completing the circuit as intended by Le Nôtre. From this point, the distortions create the illusion that the gardens are much longer than they actually are. The many discoveries made as one travels through the dynamic garden contrast the static view of the garden from the château. - Wikipedia
