[Pharo-project] Question about PBE book by newbie, instance variables

Hi, I am very new to Pharo and Smalltalk in general. When reading through the excellent PBE book i was wondering about something on page 32. In that piece of code the LOCell class is using some instance variables from it's super classes, and i was wondering if it isn't best practice to use message to self using the accessing methods so instead of. bounds := 0@0 corner: 16@16. using self bounds: (0@0 corner: 16@16). or is good to use both or is there something i don't know (maybe it is faster to use instance vars then sending a new message and traverse the inheritance tree). regards, Gerben van de Wiel