  The beginning of Yesod Mora contains a valuable survey of the sciences. This is not a formal classification of the type written by al-Fârâbî and many others, whose aim is to put in their proper place all of the sciences. Instead, Ibn Ezra critically reviews the various branches of learning which are favored by groups of Jewish scholars. There are those whose “entire wisdom” consists in masora, the traditional inventory of letters and phonetic markings in Scripture. Some are interested only in Hebrew grammar; others study only the Bible, yet others are interested only in the Talmud. None of these groups can achieve the wisdom they seek, however, without studying astronomy (hokhmat ha-mazalot). Astronomy in turn requires a foundation in geometry (hokhmat ha-middot).  Also mandatory are psychology (hokhmat ha-nefesh), which in turn has a perquisite physics, or perhaps more accurately, physiology (toledet ha-shamayim, literally “that which is produced [or induced] by the heavens”; toledet refers generally to transformations of matter, but, in Ibn Ezra’s usage, it is almost always applied to biological processes). Finally, logic (hokhmatha-mivta), “the balance of all wisdom” is also indispensable.