I shall the effect of this good lesson keep,
As watchman to my heart. But, good my brother,
Do not, as some ungracious pastors do,
Show me the steep and thorny way to heaven;
Whiles, like a puff'd and reckless libertine,
Himself the primrose path of dalliance treads,
And recks not his own rede.
O, fear me not.
I stay too long: but here my father comes.
A double blessing is a double grace,
Occasion smiles upon a second leave.
Yet here, Laertes! aboard, aboard, for shame!
The wind sits in the shoulder of your sail,
And you are stay'd for. There; my blessing with thee!
Primroses are famed for blooming early in Spring, and crop up quite frequently in Shakespeare's plays. Ophelia's mention of them here is quite a lovely inversion of her brother's concern that she, like a flower blossoming too fast, might be rejected. Shakespeare so liked the image (or got such mileage or praise for it) that it shows up again in Macbeth, Act 2 Scene 3: "the primrose way to the everlasting bonfire".
The word appears in Shakespeare only seven times, but always with the sense of dallying, of wasting time on carefree pleasures rather than anything serious. In contemporary English the word means rather more specifically a romantic entanglement - although not a very serious one. Again, Ophelia turns the tables on Laertes by inferring that it's not her that needs to be weary of the concept.
William Cecil, Lord Burghley
William Cecil, 1st Baron Burghley (13 September 1520 – 4 August 1598) was an English statesman, and the chief advisor of Queen Elizabeth I for most of her reign. When she was crowned queen in 1558, he was made her secretary. He stayed in her service until his death, and in that time he served twice as Secretary of State (1550–53 and 1558–72) and thereafter became Lord High Treasurer from 1572 until he died in 1598. His son Robert had an equally impressive political career that spanned the reigns of Elizabeth I and James I.