Alexandrians, like their predecessors, were very interested in meter and its role in poetry. The metrical "feet" in the Greek was based on the length of time taken to pronounce each syllable, with syllables categorized according to their weight as either "long" syllables or "short" syllables (also known as "heavy" and "light" syllables, respectively, to distinguish them from long and short vowels). The foot is often compared to a musical measure and the long and short syllables to whole notes and half notes. The basic unit in Greek and Latin prosody is a mora, which is defined as a single short syllable. A long syllable is equivalent to two moras. A long syllable contains either a long vowel, a diphthong, or a short vowel followed by two or more consonants.