Changes

'''Horror vacui''' (''nature's fear of [[vacuum]]'') was expression related to the belief of [[Aristotle]]'s followers denying the possible existence of empty space in [[nature]] on the grounds that where there is nothing, space cannot be defined. Wherever a vacuum would be on the threshold to develop,  the nature would not allow for it and took its place immediately. This philosofical concept stems from Aristotle's book ''Physica'' where he maintained that the nature consisted of water, earth, air and fire. The lightest element, fire, woould be directed upwards whereas the heaviest element, earth, downwards. On the other hand, the vacuum would not allow for any definition of ''"up"'' and ''"down"'' and therefore nature must abhor it.<ref name="Handbook on vacuum">{{cite book

'''Horror vacui''' (''nature's fear of [[vacuum]]'') was expression related to the belief of [[Aristotle]]'s followers denying the possible existence of empty space in [[nature]] on the grounds that where there is nothing, space cannot be defined. Wherever a vacuum would be on the threshold to develop,  the nature would not allow for it and took its place immediately. This philosofical concept stems from Aristotle's book ''Physica'' where he maintained that the nature consisted of water, earth, air and fire. The lightest element, fire, would be directed upwards whereas the heaviest element, earth, downwards. On the other hand, the vacuum would not allow for any definition of ''"up"'' and ''"down"'' and therefore nature must abhor it.<ref name="Handbook on vacuum">{{cite book

|title=Handbook of Vacuum Technology

|title=Handbook of Vacuum Technology

|author=Karl Jousten et al.

|author=Karl Jousten et al.