I had recently finished reading a book Siddha quest for immortality by Kamil Zvelebil. It was interesting book which describe the aims and lives of Siddhas and their quest for immortality.
I came across poetry of Siddhas (both from this book as well as Smile of Murugan). I liked the poems of one particular Cittar(I am comfortable with this Tamilised name Cittar).
Civavakiyar poems are very forceful , revolutionary and was sort of rebel against the Hindu and Brahminic establishment and most of his poems opposes the caste system and Brahminic rituals.
His work is called Civavakiyam. I have quoted some poems and its translation to give idea about his rebel attitude.
30.
Listen
you who take always sacred baths
you who kindle sacrifical fires
you who pour in tons of ghee
hear words of wisdom
hear
The Fires and holy waters
are within
Behold
remember and attest
An endless undiminished light
will appear and union in oneness
be
41.
The veda you recite is spit. The mantras in it are – spit.
All pleasures are but spit. All seven worlds are – spit.
Honeyed sperm is spit.Intellect is spit.Enlightment is – spit
There is nothing, indeed, nothing that is not spit!
Both poems are translated by Kamil Zvelebil
Note: The poem numbers are according to Civavakkiyam version available in Project Madurai.
கற்க... நிற்க ... 
To whom it may concern,
I came across your blog and found it very interesting. I am interested in siddha literature. I have one comment on the song of Civavakkiyar. The song you have posted as a translation by De. Zvelbil. I have one comment please see if this is correct. If you read the last line it says
Etil ecchil illatu illai- it means one that is not the ecchil- absolute, supreme being, there is nothing where it is not present. please see if I am reading correctly