food, supplies, possessions; provisions supplied to the king or a lord by a tenant or vassal; rent, feast, benefit, assylum"), from Proto-Germanic *firmō, *firχumō ("means of living, subsistence"), from Proto-Indo-European *perkwu- ("life, strength, force"). It is related to other Old English words such as feormehām ("farm"), feormere ("purveyor, grocer"), feormian ("to provision, sustain"), and feorh ("life, spirit"). The Old English word is stated by these sources as having unusually been borrowed by Medieval Latin as firma or ferma and to have provided the Old French ferme "farm", Occitan ferma "farm". This is refuted by those sources which state firma to derive from classical Latin firmus. The word continued the same senses of "rent, farmed office, source of revenue, feast". The meaning "rent, fixed payment", which was already present in the Old English word, was further strengthened due to the word's resemblance to the unrelated (so say these sources) Latin firmus ("firm, solid"), and firmitas ("security, firmness"). Valuation of a farm The tenant of a farm can only make a profit if he makes a careful assessment of its value. Although modern financial management theory has reduced such calculations to scientific formulae, the mind of the astute financier of past ages would have well understood the calculations involved, whether they were performed mentally or by making marks in the sand. An estimate is made of the long-term average yearly gross value of the revenue stream in question, which can be derived from examination of past records and accounts, adjusted for any new circumstances affecting the future. Then a discount for a risk element is deducted with a further discount deducted for the time value of money. The risk in question relates to the possibility of some of the debts forming the revenue stream being defaulted on or paid late. This causes variability in the revenue stream. The resultant figure forms the maximum rent the tenant is willing to pay to the lessor of the farm. His profit becomes the excess of whatever revenues he can extract from the farm less the rents payable, less his administration, levying and collection expenses. The skill of the tenant of a farm is therefore firstly in negotiating a favourable rent which he does by overstating the riskiness (variability) of the cash flow stream in question and secondly in his management of the debts thus assigned to him, that is to say his skills as a