The heart of Quaker ethics is summed up in the word 'simplicity'. Simplicity is forgetfulness of self and remembrance of our humble status as waiting servants of God. Outwardly, simplicity is shunning superfluities of dress, speech, behaviour, and possessions, which tend to obscure our vision of reality. Inwardly, simplicity is spiritual detachment from the things of this world as part of the effort to fulfil the first commandment: to love God with all of the heart and mind and strength.
The testimony of outward simplicity began as a protest against the extravagance and snobbery which marked English society in the 1600s. In whatever forms this protest is maintained today, it must still be seen as a testimony against involvement with things which tend to dilute our energies and scatter our thoughts, reducing us to lives of triviality and mediocrity.
Simplicity does not mean drabness or narrowness but is essentially positive, being the capacity for selectivity in one who holds attention on the goal. Thus simplicity is an appreciation of all that is helpful towards living as children of the Living God.
faith & practice, North Carolina Yearly Meeting (Conservative), 1983