A dictionary of Proverbs (Oxford Paperback Reference)

SELF-praise is no recommendation
Cf. L. laus in proprio ore sordescit, praise in one’s own mouth is offensive.

• 
  1826 COBBETT Weekly Register 17 June 743 In general it is a good rule.. that self­praise is no commendation. 1853 DICKENS Bleak House lv. Self-praise is no recommendation, but I may say for myself that I am not so bad a man of business. 1967 RIDOUT & WITTING English Proverbs Explained 137 ‘I admit I didn’t score any of the goals, but it was largely due to me that we won the game.’ ‘Self-praise is no recommendation.’ “boasting
  

SELF-preservation is the first law of nature
Cf. CICERO De Finibus IV. x. 25 primamque ex natura hanc habere appetitionem, ut conservemus nosmet ipsos, by nature our first impulse is to preserve ourselves.

• 
  a 1631 DONNE Biathanatos (1646) I. ii. It is onely upon this reason, that selfe­preservation is of Naturall Law. 1675 [MARVELL] Complete Poems (1872) I. 439 Self­preservation, Nature’s first great Law. 1681 DRYDEN Spanish Friar IV. ii. Self­preservation is the first of Laws:.. When Subjects are oppress’d by Kings, They justifie Rebellion by that Law. 1821 SCOTT Pirate I. v. Triptolemus.. had a reasonable share of that wisdom which looks towards self-preservation as the first law of nature. 1952 ‘A. A. FAIR’ Top of Heap xvii. Loyalty is a fine thing.. but self-preservation is the first law of nature. 1975 P. D. JAMES Black Tower vii. What it amounted to was that he’d do a great deal for dear Maggie but that self-preservation was the first law of nature. ■ self­preservation
  

SELL in May and go away
A saying relating originally to the cycle of activity on the London Stock Exchange. May, shortly after the start of the financial year, was a busy time, but during the following months a bear market prevailed as trading was slack and Londoners (stockbrokers included) enjoyed their summer breaks away from the capital. Also current in the expanded version represented by quot. 2002, referring to the classic St. Leger horse race run at Doncaster in early September, the traditional end of the English summer social calendar.

• 
  1979 Daily Telegraph 27 July 19 That hoary old adage sell in May and go away, has yet again been vindicated with the Financial Times 30 share index falling 97 points, from 559 on the May 4 post-election day to last night’s 462 and with little immediate relief in sight. 1992 Economist 11 July 87/1 ‘Sell in May and go away,’ says the old adage. This year it has been right on the button: a bad June for world stock-markets is being followed by a worse July. 2001 New York Times The pattern [of stock market fluctuation] is the factual basis for the saying ‘Sell in May and go away.’ 2002 Times 15 May 34 In the City, you are about as likely to hear someone utter the old adage ‘sell in May, go away, come back on St Leger’s Day’ as you are to spot gentlemen wearing bowler hats and carrying rolled umbrellas. "business