Giving another line of reasoning that proverbs should not be trusted as a simplistic guide to cultural values, Mieder once observed "proverbs come and go, that is, antiquated proverbs with messages and images we no longer relate to are dropped from our proverb repertoire, while new proverbs are created to reflect the mores and values of our time", so old proverbs still in circulation might reflect past values of a culture more than its current values. Also, within any language's proverb repertoire, there may be "counter proverbs", proverbs that contradict each other on the surface (see section above). When examining such counter proverbs, it is difficult to discern an underlying cultural value. With so many barriers to a simple calculation of values directly from proverbs, some feel "one cannot draw conclusions about values of speakers simply from the texts of proverbs". Many outsiders have studied proverbs to discern and understand cultural values and world view of cultural communities. These outsider scholars are confident that they have gained insights into the local cultures by studying proverbs, but this is not universally accepted. Seeking empirical evidence to evaluate the question of whether proverbs reflect a culture's values, some have counted the proverbs that support various values. For example, Moon lists what he sees as the top ten core cultural values of the Builsa society of Ghana, as exemplified by proverbs. He found that 18% of the proverbs he analyzed supported the value of being a member of the community, rather than being independent. This was corroboration to other evidence that collective community membership is an important value among the Builsa. In studying Tajik proverbs, Bell notes that the proverbs in his corpus "Consistently illustrate Tajik values" and "The most often observed proverbs reflect the focal and specific values" discerned in the thesis. A study of English proverbs created since 1900 showed in the 1960s a sudden and significant increase in proverbs that reflected more casual attitudes toward sex. Since the 1960s was also the decade of the Sexual revolution, this shows a strong statistical link between the changed values of the decades and a change in the proverbs coined and used. Another study mining the same volume counted Anglo-American proverbs about religion to show that proverbs indicate attitudes toward religion are going downhill. There are many examples where cultural values have been explained and illustrated by proverbs. For example, from India, the concept that birth determines one's nature "is illustrated in the oft-repeated proverb: there can be no friendship between grass-eaters and meat-eaters, between a food and its eater".