"We frequently define an acid or a base as a substance whose aqueous solution gives, respectively, a higher concentration of hydrogen ion or of hydroxide ion than that furnished by pure water. This is a very one sided definition"

This quote by Gilbert Newton Lewis is describing the meaning of an acid or a base. The standard meaning of an acid or a base is that an acid is a material whose liquid remedy provides a higher focus of hydrogen ion than that of pure water, as well as a base is a compound whose aqueous service gives a greater concentration of hydroxide ion than that of pure water. Lewis is recommending that this interpretation is also one-sided, as it does not take into account other factors that can affect the level of acidity or basicity of a substance. He is recommending that there are other variables that ought to be taken into consideration when specifying an acid or a base, such as the presence of various other ions in the remedy, the pH of the solution, and the presence of various other particles that can affect the level of acidity or basicity of the service. Lewis is suggesting that a much more comprehensive meaning of an acid or a base ought to take into consideration all of these aspects, instead of just the focus of hydrogen or hydroxide ions.