Perhaps the greatest challenge to an existential phenomenological account of perception is that posed by the argument from illusions. Recent developments in research on the behaviour of subjects suffering from illusions together with some seminal ideas found in Merleau-Ponty's writings enable us to develop and corroborate an account of the phenomenon of illusions, one, which unlike the empiricist account, does not undermine our conviction that in perception we "reach the things themselves". The traditional argument from illusions derives its force from an uncritical assumption that the process of experience takes place in time conceived as an infinite series of distinct moments. Once this assumption has been bracketed we are able to recognise the paradoxical truth that in the disillusion something can become that which it has always been and can cease to be that which it has never been. Furthermore, through a reflection on our experience of others overcoming their illusions, and on psychological evidence, we are able to show that there is nothing to suggest that this description of the disillusion is a description of a private or subjective event.