Ikiwa mita, gramu na sekunde zinabaki zikiwa thabiti, kwa nini dola inaendelea kubadilika? Vipimo vya awali ni vipimo vya kiasi thabiti cha kimwili, ilhali la mwisho ni kipimo bandia, yaani hutumika kama kipimo lakini kwa sasa hakuna kiasi thabiti cha kimwili kinachoweza kuhusishwa nacho kwa usahihi. Lakini kwa kuwa sarafu kwa sasa haiungwi mkono na kitu thabiti na kinachoshikika, idadi kubwa ya watu werevu (wasitake kukosa sehemu ya faida) hutumia muda wao kufuatilia mwenendo wa masoko ya sarafu. Badala ya kuliona kama tatizo, wanaliona kama fursa ya kupata faida zaidi. Baadhi hupata faida kwa kutabiri hatua inayofuata, huku wengine wakijaribu kupanga kwa kina mwenendo wenyewe. Sarafu au pesa ni kipimo cha thamani. Kwa maneno mengine, kiwango cha kubadilishana kwa bidhaa/huduma kwa pesa huitwa 'bei' yake. Inafaa kuzingatiwa kwamba 'thamani ya kubadilishana', au 'thamani' kama inavyoitwa kwa kawaida, ni uwiano wa kubadilishana kitu kimoja na kingine, na bei kwa hiyo ni aina ya ubadilishanaji. Lakini tofauti na ubadilishanaji wa kitu kimoja na kingine, inawezekana bei za vitu vyote zikapanda au kushuka kwa wakati mmoja. Hivyo bei ya kitu ni thamani moja tu ya kitu hicho. Kama pesa ingekuwa na thamani isiyobadilika kwa kitu thabiti na kinachoshikika (kwa mfano shilingi 1 = gramu 1 ya dhahabu), kweli ingekuwa kipimo, kama mita au sekunde. Kwa zaidi ya miaka elfu moja pesa ilitegemea kiwango fulani (kama kiwango cha dhahabu) na iliendelea kuwa njia ya kubadilishana, hivyo kwa watu wengi wa kawaida pesa kwa kawaida inaeleweka kuwa kipimo cha thamani ya vitu. Lakini uwekaji huo wa kiwango kwa kitu thabiti na kinachoshikika ulikoma katika nusu ya pili ya karne ya 20, na hivyo pesa ikaanza kuchukuliwa kuwa kitu tu, chenye thamani ya kinadharia au ya muda tu. Thamani ya kinadharia ya pesa haitegemei lazima viwango halisi vya kubadilishana na bidhaa au huduma nyingine; kwa kweli ilianza kutegemea tu mtazamo wa watu au wafanyabiashara.

If the metre, gram and second remain constant, why does the dollar keep changing? The former units are measures of stable physical quantities, while the latter is a pseudo-measure, i.e. it is used as a measure but currently no stable physical quantity can be correctly attributed to it. But as currency is currently not backed by something stable and tangible, significant numbers of bright people (not to lose out on the spoils) devote their time following the dance of the currency markets. Rather than considering it a problem, they see it as an opportunity to generate more profit. Some make profits by predicting the next move while some try to actually choreograph the dance itself. Currency or money is a unit of value. In other words, the exchange ratio of a product/service with money is called its ‘price’. It is noteworthy that the ‘value of exchange’ or ‘value’ as it is usually called, is the ratio of an exchange of one thing with another, and price therefore is a type of exchange. But unlike exchanges of one thing with another, it is possible that the prices of all things rise or fall at any one time. Hence the price of a thing is merely one of its values. If money had a fixed value in terms of something stable and tangible (for example 1 unit of money = 1g of gold), it would indeed be a measure, like the metre or the second. For more than a millennium money was based on some standard (like the gold standard) and it continued to be the medium of exchange, and hence for most ordinary people money is commonly understood to be a measure of the value of things. But that standardisation to something as stable and tangible, ceased to be the case in the latter part of the 20th century, and as such money came to be considered a mere object, which only has a notional or temporal value. The notional value of money may not necessarily be based on real exchange ratios with other commodities or services; in fact it came to be based merely on the perception of people or traders.

Kwa hiyo, bei au thamani ya vitu hubadilika kulingana na thamani ya kiasi cha fedha, kiasi hicho hicho au hata zaidi ya umuhimu au manufaa ya bidhaa au huduma, yaani "thamani ya manufaa". Kwa bahati mbaya, ndivyo vitu vinavyothaminiwa katika ulimwengu wa leo; kwa hiyo haishangazi kuona thamani ya nyumba yako ikipanda na kushuka, na kwa zaidi ya karne moja kumekuwa na mazungumzo kuhusu kupanda na kuanguka kwa uchumi angalau mara moja kila muongo kwa zaidi ya miaka 150.

So, the price or value of things fluctuates according to the notional value of money, as much or even more than the importance or benefit of the product or service, or the ‘value of benefit’. This is unfortunately how things are valued in today’s world – hence it is not surprising to find the value of your house rising and falling, and for over a century there has been talk about boom and bust at least once every decade for over 150 years.