I am reading *Candide* by Voltaire. Candide urges a sick man to find a cure for his illness, and [the man responds with](http://books.google.com/books?id=1Pa9M5pEMD4C&pg=PT16&lpg=PT16&dq=%22taking+a+glister%22&source=bl&ots=B_sHJhXZA6&sig=EFQhavvHBHuImJA3443xQoOd_eY&hl=en&sa=X&ei=KgS0UrDzB6LcyQG_7YCABw&ved=0CFEQ6AEwBA#v=onepage&q=%22taking%20a%20glister%22&f=false)

> "Alas! how can I?" said Pangloss, "I have not a farthing, my friend, and all over the globe there is no letting of blood or taking a glister, without paying, or somebody paying for you."

A search of the word [*glister*](http://www.thefreedictionary.com/glister) typically redirects to *glisten* or *glitter*. But these lead to the expected definitions about the behavior of light.

Searching the phrase *taking a glister* led to a [result](http://books.google.com/books?id=x3JZAAAAYAAJ&pg=RA1-PA76&lpg=RA1-PA76&dq=%22taking+a+glister%22&source=bl&ots=1_D7mQke3a&sig=hudOy3tiy65efVXCDGu5pYO2O6Y&hl=en&sa=X&ei=KgS0UrDzB6LcyQG_7YCABw&ved=0CEQQ6AEwAQ#v=onepage&q=%22taking%20a%20glister%22&f=false) that claims the action can break a fast, which may imply impurity or consumption. 

From the information I found I think it may be:

 1. Slang for a hygienic (like "take a shower") or [medical](http://books.google.com/books?id=n8oyAQAAMAAJ&pg=PA247&lpg=PA247&dq=%22taking+a+glister%22&source=bl&ots=Tslhwu3Uih&sig=vBIgLg0O-YwFXPUkMoR4e7J_Ti4&hl=en&sa=X&ei=KgS0UrDzB6LcyQG_7YCABw&ved=0CGUQ6AEwCQ#v=onepage&q=%22taking%20a%20glister%22&f=false) (with "letting of blood") practice 
 2. A [form of measurement](http://books.google.com/books?id=hO12khIkc-gC&pg=PT166&lpg=PT166&dq=%22take+a+glister%22&source=bl&ots=JdBT6pKKAO&sig=toQweiR4c2TR8RCFHqBWRDhPoi8&hl=en&sa=X&ei=lgm0Up3bF4X4yAHTMg&ved=0CCwQ6AEwAA#v=onepage&q=%22take%20a%20glister%22&f=false), perhaps like "take a pill" 

What does the phrase "taking a glister" mean?