Even though Saeedi, Logothetis et al. (2024) have concluded that visual illusions are a product of extrastriate rather than striate mechanisms (based on neural response latencies of illusions versus real-images as well as the optogenetic silencing of the object-encoding area of extrastriate cortex), we suspect that ultimately the creation of the mismatch is due to a discrepancy between the efference-copy representation stored in the cerebellum (perhaps going back to the time of development) and the real-world representations contained in the cortical sensory systems (Tehovnik, Hasanbegović, Chen 2024). The reason for this is that the cerebellum, with its disproportionate number of neurons (Herculano-Housel 2009), is the structure whose job it is to put all the senses in register with the motor system. For example, Hebb (1969) observed that a subject donning a prism that bent an otherwise straight line eventually adapts such that if asked to draw a straight line by hand, for example, the line to an outside observer would be deemed straight even though initially (before adaptation) this line appeared curved to the subject wearing the prism. That the cerebellum is necessary for prism adaptation as well as other types of sensory-motor realignments is well accepted (Bell, Sawtell et al. 2008; Braizer and Glickstein 1973,1999; Gallistel et al. 2022; Gilbert and Thach 1977; Giovannicci et al. 2017; Guell et al. 2018; Heun et al. 1999; Ito 2008; Kitazawa et al.1998; Miles and Lisberger 1981; Robinson 1981; Soetedjo and Fuchs 2006; Soetedjo et al. 2008; Smaers et al. 2018; Swain et al. 2011; Thach et al. 1992). It is this re-alignment that permits for highly automated acts to be executed precisely and at the shortest latencies by all vertebrates. Indeed, in the 14th Century, Pope Benedict XI set out to have the wall of St. Peter’s cathedral remodeled. To accomplish this, applicants were required to submit their art, but Giotto di Bondone (1267-1337) did not have any art to submit, so he took out a sheet of paper upon which he drew a perfect circle. Today in Tuscany this circle is known as ‘The round O of Giotto’ (Schiller and Tehovnik 2015). Without the cerebellum, Giotto’s circle would not have been precisely round, a perspective to have by anyone remodeling a building.