A Letter To Dr. Helsham

SIR,
Pray discruciate what follows.
The dullest beast, and gentleman's liquor,
When young is often due to the vicar,[1]
The dullest of beasts, and swine's delight,
Make up a bird very swift of flight.[2]
The dullest beast, when high in stature,
And another of royal nature,
For breeding is a useful creature.[3]
The dullest beast, and a party distress'd,
When too long, is bad at best.[4]
The dullest beast, and the saddle it wears,
Is good for partridge, not for hares.[5]
The dullest beast, and kind voice of a cat,
Will make a horse go, though he be not fat.[6]
The dullest of beasts and of birds in the air,
Is that by which all Irishmen swear.[7]
The dullest beast, and famed college for Teagues,
Is a person very unfit for intrigues.[8]
The dullest beast, and a cobbler's tool,
With a boy that is only fit for school,
In summer is very pleasant and cool.[9]
The dullest beast, and that which you kiss,
May break a limb of master or miss.[10]
Of serpent kind, and what at distance kills,
Poor mistress Dingley oft hath felt its bills.[11]
The dullest beast, and eggs unsound,
Without it I rather would walk on the ground.[12]
The dullest beast, and what covers a house,
Without it a writer is not worth a louse.[13]
The dullest beast, and scandalous vermin,
Of roast or boil'd, to the hungry is charming.[14]
The dullest beast, and what's cover'd with crust,
There's nobody but a fool that would trust.[15]
The dullest beast, and mending highways,
Is to a horse an evil disease.[16]
The dullest beast, and a hole in the ground,
Will dress a dinner worth five pound.[17]
The dullest beast, and what doctors pretend,
The cook-maid often has by the end.[18]
The dullest beast, and fish for lent,
May give you a blow you'll for ever repent.[19]
The dullest beast, and a shameful jeer,
Without it a lady should never appear.[20]
Wednesday Night.
I writ all these before I went to bed. Pray explain them for me, because
I cannot do it.