In the greek islands

In the greek islands
 

15/4/12 S

-In the Greek islands, the locals have an unusual way of celebrating Easter.

What's the difference between in and on?

'In' and 'on' are seldom interchangeable, as they both have a specific set of meanings.
'In' usually includes the notion of 'within'.

In the house (within it)
On the house (on its surface)

However, both 'in the islands' and 'on the islands' can mean the same thing, when talking about place, location, situation, etc.

Thank you, but is it correct to say that 'in/on' can both be used for

__ an island?

Not in that context, no. If you use 'in' it sounds like you're underground.

The way it appears in the original sentence you provided, it's OK to use either preposition because the meaning is the same either way. The context is a situation-about how Easter is celebrated-and the locale is being provided. 'In' is preferred over 'on' to express this idea.

I think I've spotted a possible difference in how we view "on/in the Greek Islands" (which mean the same thing) compared to "on/in an island" (which mean different things).

The expression "the Greek Islands" can be perceived in two different ways:

(a) physically, as a collection of small land-masses, and
(b) politically, as a region inside of a boundary.

"On the Greek Islands" refers to physical location on one of the land-masses.

"In the Greek Islands" refers to physical location inside the politically-defined boundaries of the region that contains the Greek Islands.

We perceive the expressions "in an island" and "on an island" as having different meanings because we normally think of "an island" as a physical object and not as a polticially-defined region.

Thank you.

Then are in and on just the same?

-a book of instruction in a particular subject
-a book of instruction on a particular subject

In this type of context, no, they are usually not the same. For example, these two phrases have different meanings.

"A book on Chinese" discusses something about the Chinese language, but it may be written in any language. Here "on" identifies the content, but not the medium.

"A book in Chinese" is written in the Chinese language, but the content may be anything. Here "in" identifies the medium, but not the content.

Thank you, but then what's the difference between
-a book of instruction in a particular subject
-a book of instruction on a particular subject

'subject' can't be a medium.

It should be 'a book of instruction on a particular subject'. The first sentence doesn't sound right.

You may also use 'about' instead of 'of'.

Thank you, but what do you think 'a book of/about instruction' is? Is it a manual, a guide, or?

Oops! I meant 'about' may replace 'on'.
A book of instruction on/about a particular subject.

Sorry about the confusion.

A book of instruction is usually a called a manual or a guide.

Thank you.