Illusions are created, as in ‘Artists can create an illusion of a three-dimensional image on a two-dimensional surface’ and people entertain, harbour, labour under or are under various illusions, as in ‘I harbour no illusions about the complexity of the task ahead’ or ‘She’s under the illusion that she can simply ask for her money back if something goes wrong’. This is going to be hard work!’ In the belief that things are better or will be better than they actually are, illusions can be grand or romantic, as in ‘Fortunately, when they chose life on the farm, they had no romantic illusions’. Illusions are by their very nature false, as in ‘Don’t be under any false illusions.
The latter meaning can apply to various illusions that relate to the senses, these being auditory, optical, perceptual, sensory or visual, as in ‘People have always been intrigued by optical illusions such as stairs that appear to be leading both up and down at the same time’.
