Of course, from a Google standpoint, quality is determined based on quantity. If you consider pagerank as Google's quantification of what they consider the relative quality of a web site (which is more or less the language used in the original patent filing) quantity of links is what determines the quality of pages, so the higher the quality of the sites that link to you the more sites that link to them and so on.

But I tend to agree that the quality of the link, both in terms of pagerank and relevance, is more important because one high quality link can have more impact in the SERPs than dozens of low quality links.

__________________
The best way to learn anything, is to question everything.