For the sake of convenience, people then agreed to deal in something that is intrinsically useful and easily applicable, such as iron or silver.
fɚðə sˈeɪk ʌv kənvˈiːnɪəns, pˈiːpəl ðˈɛn ɐɡɹˈiːd tə dˈiːl ɪn sˈʌmθɪŋ ðæt ɪz ɪntɹˈɪnsɪkli jˈuːsfəl ænd ˈiːzili ɐplˈɪkəbəl, sˈʌtʃ ɐz ˈaɪɚn ɔːɹ sˈɪlvɚ.