Yf my deare love were but the childe of state,
It might for fortunes basterd be unfathered,
As subject to times love, or to times hate,
Weeds among weeds, or flowers with flowers gatherd.
No it was buylded far from accident,
It suffers not in smiling pomp, nor falls
Under the blow of thralled discontent,
Whereto th'inviting time our fashion calls:
It feares not policy that Hereticke,
Which workes on leases of short numbred howers,
But all alone stands hugely pollitick,
That it nor growes with heat, nor drownes with showres,
To this I witnes call the fooles of time,
Which die for goodnes, who have liv'd for crime.
Changes to the original text; line 14, 'foles' changed to 'fooles'.
For an understanding of the poem as a whole , one must bear in mind that 'it' consistently refers to 'my deare love'.
In the first quatrain, the poet notes that if his love was a thing of this world (the childe of state) it might be unseated (it might for fortunes basterd be unfathered), subject to times changeability (to times love or to times hate), and be gathered in as a weed or as a flower. There may be an echo in the expression 'childe of state' of the fact that Southampton was a ward of the crown.
In the second quatrain, the poet claims that his love was not built by chance (buylded far from accident), is not subject to deceit by flattery (suffers not in smiling pomp), nor suffers the discontent which fashion encourages.
In the third quatrain, the poet claims that his love has nothing to fear from those who are motivated by worldly concerns (policy that Hereticke) which has short term considerations (works on leases of short numbred howers), but stands alone, not subject to change with heat or rain.
In the final couplet, the poet asks those who are subject to times vagaries (the fooles or time) to bear witness to everything he has said. These fools he characterises as men who die for goodness but have lived in crime ie who repent their sins at the end of their life. There is a certain delicious irony in asking these changeable men to bear witness to the unchangeability of the poet's 'deare love'.
Note that the beloved is absent from all this trafficke between the poet, his love and time. Note also that 'my deare love' could be construed as referring to the beloved, except that it is referred to as 'it' consistently in the poem. What a subtle rogue, this Shakespeare!